Contents

About This Guide

The eBidyaloy SC-991BF is an on-screen scientific calculator emulator for classrooms and study — available on Windows, macOS, Web, Android and iOS. It reproduces a modern ClassWiz-style scientific calculator: a natural “textbook” display, 13 calculator apps, physical constants, unit conversions, and a live step-by-step explainer for teaching.

How to read the key operations

Key presses are shown as chips, e.g. 7 × 8 EXE. A key’s SHIFT function (orange label above the key) is written SHIFT then the key; a VARIABLE letter (gold) is entered from the VARIABLE menu.

Keys & Key Markings

The SC-991BF keypad is arranged in the same zones as a modern scientific calculator: a title strip, the LCD, a control cluster, five soft keys, two scientific rows, and the number pad.

Key Markings — three functions per key

Control Cluster

Soft Keys

Scientific Keys

Number Pad

Menu-Operation Shorthand

To keep instructions short, this guide writes menu paths in a compact form. For example:

…is the same as the full operation:

Entering & Editing Calculations

The SC-991BF uses natural textbook input (MathI): fractions, roots, powers and other expressions appear on screen just as they are written on paper. You type an expression from left to right and press EXE to evaluate it. (By default results are shown in their exact “Standard” form — a fraction, surd or π; press ⇄ to switch to the decimal, or see Input/Output in SETTINGS to show decimals first.)

Keys such as ▢∕▢ (fraction), √▢ (root) and ▢^ (power) insert an empty template with boxes to fill. Type into the highlighted box, and press ▶ to move out of it and continue the calculation.

Moving the cursor

Use the arrow keys to move the flashing cursor through an expression without erasing anything:

Deleting and inserting

To correct a mistake, move the cursor to the spot and use:

Using INS — wrap a value into a function

Sometimes you have already typed a value and then realise it should sit inside a function — for example you typed 30 but wanted √30. Instead of deleting and retyping, place the cursor to the left of the value, press SHIFT DEL (INS) to arm it, then press the function key. The function is inserted and the value to its right is pulled into the function's argument automatically.

INS arms these function keys: √▢ (and ∛), sin, cos, tan (and their inverses), ln and log. The value it grabs is the next number, the next parenthesised group, or the next single template (fraction, root, variable…).

Correcting after a result

After you press EXE and see a result, you have two choices:

• Begin a new calculation — just start typing, and the previous entry is cleared.
• Edit the previous entry — press ◀ or ▶ to bring the expression back with the cursor in it, change what you need, and press EXE again.

When a calculation has an error

If you press EXE on an expression the calculator cannot evaluate, it shows an error message — most often Syntax ERROR or Math ERROR, sometimes a more specific name (see Error Messages in the appendix) — and returns you to the expression with the cursor placed at the point that caused the error — not at the end of the line. You can start fixing straight away without hunting for the fault. For example, an unmatched bracket or a stray operator leaves the cursor exactly where the parser stopped; a Math ERROR such as division by zero leaves it on the offending term.

The calculator keeps your last 30 calculations. From a result, press ▲ to step back through previous entries and ▼ to step forward. A recalled entry can be re-used in two ways:

• Press EXE to re-run the recalled calculation as it is.
• Move the cursor into it, edit the expression, then press EXE to evaluate the changed version.

Reusing the last answer with Ans

The result of the most recent calculation is held in Ans. Start a new calculation with an operator (for example + or ×) and the calculator inserts Ans automatically, or press Ans to use it anywhere in an expression.

Using Menus & Settings

Many operations use menu screens. Press ⚙ while using a calculator app to open the SETTINGS menu shown below. Each item with a ▸ opens a further menu.

The SETTINGS menu has two groups: Calc Settings (how calculations behave and display) and Reset. Drill in with OK; each setting shows a numbered list of options to choose from.

Calc Settings

Reset

Using CATALOG, FUNCTION & TOOLS

Three soft keys along the top of the keypad — CATALOG, FUNCTION and TOOLS — open on-screen menus that reach the calculator's advanced commands without dedicated keys. What each menu offers depends on the app you are in, so the same key does the right thing in Calculate, Complex, Spreadsheet and the rest. This chapter explains all three, with worked examples.

Press CATALOG to open a scrollable list of the commands, functions and symbols available in the current app. Move the highlight with ▲ ▼, press OK to insert (or run) the selected item, and press ↺ to close without inserting.

CATALOG list

Function Analysis

These build a calculus or algebra template with empty boxes; type into each box and move between them with ▶ or the D-pad, then press EXE.

Numeric commands

Hyperbolic functions

Special commands (they act, not insert)

These CATALOG entries operate on the expression or result already on screen rather than inserting a template.

Defining your own functions — f(x) and g(x)

The Table app lets you register two functions f(x) and g(x), but you can also define them right here in Calculate. Type an expression in x, then choose Define f(x) (or Define g(x)) from the CATALOG. The line is stored, and f(▢) / g(▢) become callable from any app — no need to open the Table app. Definitions persist until you overwrite them or reset.

CONST — physical constants (CATALOG → CONST ▸)

CONST ▸ opens a menu of scientific constants (CODATA-2022) in six categories. Choose a category, then a constant, to insert its value into your calculation.

CONV — unit conversions (CATALOG → CONV ▸)

CONV ▸ applies a unit conversion to the value on the display. First compute a value, then choose a category and a conversion; the result is replaced by the converted value.

Press FUNCTION to insert the functions that describe a number's size, angle and parts. Abs works on any real or complex value; arg, Conjg, ReP, ImP and the polar operator ∠ are used with complex numbers. Highlight an item, press OK to insert it, and the caret lands inside its parentheses.

Press TOOLS to reach tools for the app you are in. TOOLS is context-sensitive — it holds editing and app operations, not result-format conversions. (Those live on the ⇄ FORMAT key and the CATALOG; see the table below.)

TOOLS in Calculate — Undo / Redo

TOOLS in the data apps — row editing

In the list-based apps, TOOLS edits the data list. In Statistics you can also sort:

Where the result-format conversions live

Conversions such as S⇔D, recurring decimal, engineering form and prime factorisation are not on the TOOLS menu. Reach them here:

Calculator Apps

Press ⌂ to display the HOME screen — the menu of all installed calculator apps. Use ▲ ▼ ◀ ▶ to move the highlight to an app, then press OK. Alternatively, press the number key shown on an app’s icon (its option number) to open it directly.

When you open an app you see either a calculation screen or a short menu to choose the calculation type. Each app is documented in full — every function with worked examples — in the chapters that follow.

Extended Display & Explainer

When teaching with the SC-991BF on a large screen, open the extended display with the ⧉ (cast) button in the title bar. A greatly enlarged copy of the calculator’s LCD appears beside the keypad so the whole class can read the current expression and result. The panel is marked LIVE DISPLAY and refreshes automatically as you type.

Below the extended display, the explainer turns any Calculate result into a lesson. It has two tabs:

• EXPLANATION — a plain-language walkthrough of what each function and operation does, in order.
• STEPS — the working shown as a reduction: the expression is rewritten one step at a time, each line a little more simplified, down to the final answer (shown in green).

Example 1 — roots and arithmetic

Example 2 — trigonometry (Degree)

Example 3 — powers

Example 4 — logarithms

Example 5 — implicit multiplication priority

Example 6 — order of operations

Sharing Calculations (QR & Link)

Any result on the SC-991BF can be turned into a QR code and a shareable web link. A student scans the code (or opens the link) to see the calculation on a phone or computer — typeset neatly, with the step-by-step working and, where it applies, a graph. It is the fastest way to put a worked example on the board, into a worksheet, or into a chat with a student.

Sharing works in every app

Sharing is not limited to the Calculate app. Press SHIFT Ans on the result screen of any app — Statistics, Equation, Matrix, Vector, Complex, Base-N, Distribution, Inequality, Ratio or Table — and that result is shared with its heading, its answer (matrices and tables included) and its working.

Opening a shared link shows a clean, read-only page with the calculation rendered in proper mathematical notation. Depending on the app, the page can include:

• Typeset math — the expression and answer in textbook form (fractions, roots, powers, matrices).
• A graph — for Table (the function curve), Statistics (the scatter of points with the fitted regression line) and Distribution (the normal curve or probability bars).
• Step by step — the same teaching breakdown the calculator's explainer shows.
• Institute name — when shared from a signed-in institute account, the page shows which institute it came from.

Sample shared page (with a graph)

Open in calculator

A shared Calculate link also offers “Open in calculator”, which reloads the exact expression back into the SC-991BF so it can be edited and re-run. This needs an eBidyaloy account with the calculator enabled; anyone else can still read the shared page.

Calculate App Reference

The Calculate app is the calculator's main workspace. Enter an expression in natural textbook format and press EXE to evaluate it. This chapter covers every function available in Calculate, grouped by type, each with a worked example.

Basic Arithmetic & Priority

Use + − × ÷ for the four operations and ( ) to group terms. Calculations follow standard priority: functions and powers first, then × ÷, then + −. An omitted × (implicit multiplication) before a bracket or constant binds tighter than ÷.

Fractions

Press ▢∕▢ for a fraction template and SHIFT ▢∕▢ for a mixed number. With the default MathO output a result appears as the exact fraction; press ⇄ (FORMAT / S⇔D) to switch to its decimal value (or select DecimalO to show the decimal first).

Powers & Roots

▢² squares, SHIFT ▢² cubes, ▢^ raises to any power, √▢ is a square root, SHIFT √▢ a cube root, and SHIFT ▢^ gives the x-th root.

Exponential & Logarithmic

log is base-10 log, ln is natural log, SHIFT log is 10ˣ, SHIFT ln is eˣ. Use the CATALOG log▢(▢) for a logarithm to any base.

Trigonometric Functions

sin cos tan and their inverses (SHIFT + the key) use the current Angle Unit. Append ° ʳ ᵍ (from CATALOG) to give a value in a specific unit regardless of the mode.

Hyperbolic Functions

The hyperbolic functions sinh, cosh, tanh and their inverses are on the CATALOG menu.

Percentage

Enter a value followed by SHIFT ( (the % operator). A percentage is interpreted as “per hundred”.

Permutation, Combination & Factorial

SHIFT × is nPr, SHIFT ÷ is nCr, and x! (factorial) is on the CATALOG menu.

Numeric Functions

The CATALOG provides Abs (absolute value), Int (truncate), Frac (fractional part), Intg (floor), Rnd (round to the display) and x⁻¹ (reciprocal).

GCD, LCM & Random

From the CATALOG: GCD(, LCM(, RanInt#( (a random integer in a range) and Ran# (a random number in [0, 1)).

Calculus — Derivative & Integral

The CATALOG offers d/dx (numerical derivative at a point) and ∫dx (definite integral between limits).

Summation & Product

Σ sums and Π multiplies an expression as a counter runs from a lower to an upper limit.

SOLVE, CALC & VERIFY

SOLVE finds a root of f(x) = 0 by Newton's method. CALC evaluates an expression after prompting for each variable. VERIFY tests whether a relation (=, ≠, <, >, ≤, ≥) is true.

Coordinate Conversion

Pol( converts rectangular (x, y) to polar (r, θ); Rec( converts polar (r, θ) back to rectangular (x, y). Both are on the CATALOG.

Variables & Independent Memory (M)

The calculator has ten memories — A B C D E F x y z and the independent memory M — that each hold one number. Press VARIABLE to open the menu, highlight a memory with ▲ ▼ and press OK; a small action menu then appears offering Recall or Store (M additionally offers M+ and M−).

To store a value into a memory (for example, save 5 into A):

1. Type the value — 5 — on the line. (Leave the line empty to store the last answer, Ans, instead.)
2. Press VARIABLE to open the memory list.
3. Highlight the memory (A) with ▲ ▼ and press OK.
4. Choose Store. The value is now held in A until you overwrite it or reset the memory.

To recall a stored value: press VARIABLE, highlight the memory, press OK, then choose Recall — the stored value drops straight into whatever you are calculating.

Storing a result from another app

You are not limited to storing from Calculate. On the result screen of the Equation solver, Distribution, Vector, Complex or Matrix app, press VARIABLE and the displayed value is captured; pick a memory (A–F, x, y, z) to store it. This lets you carry a solved root, a probability, a dot product or a determinant straight into a follow-up calculation without copying it down.

Ans, π, e & Constants

Ans reuses the previous answer; SHIFT 7/8 insert π and e. Physical constants come from CATALOG → CONST ▸.

Standard Form (a × 10ⁿ)

Press ×10ˣ to type a power-of-ten exponent directly — the natural way to enter very large or very small numbers. To have results shown in standard form, set ⚙ − [Calc Settings] > [Number Format] > [Sci].

The ×10 Key setting (⚙ ▸ Calc Settings) chooses what that key inserts. With Sci-Notation it inserts a compact ᴇ exponent mark; with Power it inserts a written-out ×10^ expression. Both evaluate identically.

Result Formats & Tools

After a result, ⇄ (FORMAT / S⇔D) toggles exact ⇄ decimal, and the full FORMAT menu (SHIFT ⇄) offers Prime Factor, Recurring Decimal, Sexagesimal, Standard Form and the fraction forms. The CATALOG adds ENG (engineering form), FACT and RECUR. (The TOOLS key here is Undo / Redo — see the CATALOG chapter.)

Typing a recurring decimal

You can also enter a recurring decimal directly, using the CATALOG command ▨̄ input recurring. It inserts an overline block; type the repeating digits inside it, then press ▶ to leave the block. The calculator uses the exact value in the calculation.

The FORMAT menu — every result conversion

All result conversions live on the FORMAT menu, opened with SHIFT ⇄ (or a bare ⇄ when the FORMAT Key setting is “Format Menu”). Each item reshapes the current result without retyping it; only the ones that make sense for the result are active.

Statistics App Reference

The Statistics app summarises a set of data and fits regression models. You type values into a list, then read off statistics such as the mean, standard deviation and quartiles; for paired data it also finds the line or curve of best fit. Open it from HOME by pointing to Statistics and pressing OK.

Choosing an analysis type

Entering data

Type a value and press EXE to drop to the next row. Move with the arrow keys, overwrite a cell by typing over it, and delete a value with DEL. Press TOOLS on the data editor for the row tools — Insert Row, Delete Row, Delete All and Sort Ascending / Descending (see “Editing and extending the data list” below). To weight values by how often they occur, turn on the Frequency column from ⚙ → Statistics ▸ Frequency ▸ On.

1-Variable statistics

Enter the data with:

Normal distribution from 1-variable data

On the 1-variable result screen, press EXE to open the Norm-Dist tools. They convert a data value x to a probability using the fitted mean and σ: P(t) is the lower-tail area Φ(t), Q(t) = Φ(t) − 0.5, R(t) = 1 − Φ(t), and ▸t standardises x into t = (x − x̄) / σₓ.

Two-variable regression

Choose a 2-variable model to get an x and a y column. Enter each pair, then press FUNCTION for the fitted coefficients and the correlation r.

The other regression models

The logarithmic, ab-exponential and inverse models are fitted exactly like the ones above — choose the shape that matches your data, enter the pairs, and press FUNCTION. Each reports its own a, b (and correlation r).

Switching the model without re-entering data

All seven 2-variable models use the same (x, y) columns, so you can try a different fit on the same data without retyping it. On the regression result screen press FUNCTION to open Select Reg Type, choose a model (▲▼ and OK, or the number keys 1–7), and the calculator re-fits the entered pairs and shows the new coefficients. This makes it easy to compare, say, a linear against a quadratic fit and read off which has the better correlation.

The full 2-variable statistics list

Beyond the fit coefficients, a 2-variable result lists every summary statistic — the running sums, both standard deviations for x and y, and the data ranges. Scroll the result with ▼ to reach them.

Editing and extending the data list

You can revise the data at any time without leaving the app. Move the cursor with the arrow keys and:

• Correct a value — point to the cell, type the new value and press EXE; it replaces the old one.
• Clear a cell — empty it with DEL. A blank row is simply skipped when the statistics are calculated, so you don't have to shuffle the rows below.
• Add more data — scroll to the first empty row at the bottom of the list and keep typing.

To reshape the list itself, press TOOLS on the data editor for the row tools:

• Insert Row — push a blank row in above the highlighted row (so you can add a value you missed between two others).
• Delete Row — remove the highlighted row and close the gap.
• Delete All — clear the whole list to start over.
• Sort Ascending / Descending — reorder on whichever column the cursor is in (x, y or Freq). A paired list is kept aligned, so each x keeps its own frequency or y partner. Note that a sort cannot be undone — the original order is not recoverable.

Press FUNCTION again after any change and every statistic is recomputed from the current list.

Statistics calculation screen

The Statistics Calc screen (TOOLS ▸ Stat-Calc from a result) is a free-form editor in which you can recall any statistical value by name and combine it with ordinary arithmetic. Press VARIABLE to pick the value to insert. The available values are:

Estimating x from a quadratic fit

For a linear model, estimating x from a y value gives a single x̂ (Example 6). A quadratic model is not one-to-one, so a given y can correspond to two x values — the calculator returns both, x̂₁ and x̂₂.

Statistical calculation formulas

For reference, these are the formulas the app uses. Sums run over all n data values (weighted by the Frequency column when it is on).

Linear regression y = a + bx:

Quadratic regression y = a + bx + cx² — the coefficients a, b, c come from the least-squares normal equations, and x is estimated from a y value by solving the quadratic:

Distribution App Reference

The Distribution app evaluates the common probability distributions. Choose a distribution from the menu, enter its parameters, and read the probability — or, for the list distributions, a whole table of probabilities.

Choosing a distribution

Normal distribution

Binomial distribution (list input)

Enter N (trials) and p (success probability) once, then a growable list of x values; a probability is returned for each. PD gives P(X = x); CD gives P(X ≤ x).

Poisson distribution (list input)

Valid parameter ranges

Each distribution accepts parameters only within its natural range; a value outside the range produces a Math ERROR. Re-enter a value inside the range to continue.

Table App Reference

The Table app tabulates one or two functions over a range of x — ideal for plotting points, spotting where a function crosses zero, and comparing two functions side by side.

Defining the function(s) and range

Type the formula for f(x) using the x key for the variable. To tabulate a second function, turn on g(x) from ⚙ → Table ▸ f(x)/g(x). The calculator then asks for Start, End and Step and builds a row for each x (up to 45 rows for a single function, or 30 rows when both f(x) and g(x) are tabulated).

Enter the function with:

Registering & using f(x) and g(x)

Defining a function in the Table app also registers it. Once f(x) (and optionally g(x)) is entered, you can call it by name in the Calculate app: insert f(▢) or g(▢) from the CATALOG and type a value for x in the box. This lets you reuse a formula without retyping it.

Equation App Reference

The Equation app solves two kinds of problem: simultaneous linear systems with 2, 3 or 4 unknowns, and polynomial equations of degree 2, 3 or 4. You enter only the coefficients and the calculator returns the complete solution set.

Choosing an equation type

Simultaneous equations

Each row of the grid is one equation. For 2 unknowns the columns are x, y and the constant =. Enter the coefficients left to right, pressing EXE after each.

Key operation:

Polynomial equations

Enter the coefficients from the highest power down. The quadratic x² − 5x + 6 = 0 uses a = 1, b = −5, c = 6.

Minimum / maximum of the curve

After you solve a quadratic or cubic, the result screen also reports the turning point(s) of the curve y = f(x): a quadratic has a single vertex (its minimum if a > 0, maximum if a < 0); a cubic has a local maximum and a local minimum when its shape has them.

Complex roots

When a polynomial has non-real roots, the Complex Roots toggle decides whether they are shown. It is Off by default (only real roots appear). Turn it on from the Equation TOOLS menu → Complex Roots ▸ On.

Solver — one equation in x

The Solver is the last item on the type menu. Instead of coefficients you type a whole expression f(x) (or an equation L = R), and the calculator finds a value of x that makes it zero using Newton's method, starting from the current value of x.

Inequality App Reference

The Inequality app solves a polynomial inequality and reports the solution as a set of intervals on the number line. It handles quadratic, cubic and quartic inequalities against 0.

Choosing degree and direction

Complex App Reference

The Complex app performs the four operations on two complex numbers z₁ = a + bi and z₂ = c + di, and can show the result in rectangular (a + bi) or polar (r∠θ) form. The imaginary unit i satisfies i² = −1.

Selecting the operation

Polar form and complex functions

Set Complex Result ▸ r∠θ in SETTINGS to read a result in polar form. The FUNCTION menu inside the app also offers Abs (modulus |z|), arg (argument), Conjg (conjugate z̄), ReP (real part) and ImP (imaginary part).

Powers and functions in the Calculate app

The Complex app is a guided z₁ ∘ z₂ workspace. For anything richer — powers of a complex number, longer expressions, or the FUNCTION functions applied on their own — use the Calculate app, where you type i with the i key and enter a free expression. Complex results there obey the same FUNCTION menu (Abs, arg, Conjg, ReP, ImP) and the SETTINGS r∠θ output.

Base-N App Reference

The Base-N app works with whole numbers in four bases — DEC (10), HEX (16), OCT (8) and BIN (2) — and includes the bitwise logic operators. All arithmetic is integer arithmetic on a 32-bit two's-complement value.

Switching base

The active base is shown at the top of the screen. Press the base soft keys DEC, HEX, OCT, BIN to re-display the current value in another base — the value never changes, only its notation.

Arithmetic in the active base

The four operations + − × ÷ (and parentheses) work directly on numbers in the current base; the result is displayed in that base. Only digits the base allows can be entered (0–1 for BIN, 0–7 for OCT, 0–9 and A–F for HEX).

Mixing bases with per-value prefixes

From the CATALOG you can tag an individual number with the base to read it in, whatever the active base: d→ (decimal), h→ (hexadecimal), b→ (binary) and o→ (octal). This lets you combine values written in different bases in one calculation.

Bitwise logic operators

Press CATALOG in Base-N to insert a logic operator: and, or, xor, xnor, not and Neg (two's-complement negate). These operate on the binary bit patterns.

Negative values

Decimal shows a signed value; the other bases show the 32-bit two's-complement bit pattern, so a negative number prints as its unsigned pattern.

Matrix App Reference

The Matrix app performs calculations with matrices of up to four rows and four columns (and rectangular m×n matrices). You store values in the matrix memories MatA, MatB, MatC and MatD, then build an expression from them. The result of every matrix calculation is retained in a special memory called MatAns, which you can feed straight into the next calculation.

Creating and entering a matrix

When you open an operation, the calculator first asks for the dimensions (rows × columns), then shows an empty grid. Fill it cell by cell, pressing EXE after each value to advance to the next cell. This grid holds MatA = 2111:

Addition and Subtraction

Multiplication

Powers — Square and Cube

A square matrix can be raised to a power. MatA² means MatA × MatA, and MatA³ means MatA × MatA × MatA.

Inverse

The inverse MatA⁻¹ is the matrix that satisfies MatA × MatA⁻¹ = I (the identity). It exists only for a square matrix whose determinant is non-zero.

Determinant

The determinant is a single number describing a square matrix. For 1×1, 2×2 and 3×3 matrices it is computed as:

Transpose

The transpose Mᵀ turns rows into columns. It works for any matrix, including rectangular ones.

Identity Matrix

Identity(n) creates the n×n identity matrix — 1s on the main diagonal and 0s everywhere else. Multiplying any matrix by the identity leaves it unchanged. The size n may be 1 to 10; a value outside that range gives an Argument ERROR.

Reusing a result — MatAns

Every matrix result is held in MatAns. On a result screen press EXE to carry it straight into the next calculation as operand A, without re-entering it.

Copying a result into MatA–MatD

MatAns is overwritten by the next matrix calculation. To keep a result, copy it into one of the named matrices. On a matrix result screen press VARIABLE and choose the destination — MatA, MatB, MatC or MatD; the whole matrix (its dimensions and every element) is stored there.

Absolute value of a matrix

Applying Abs to a matrix takes the absolute value of every element, returning a matrix of the same size. Insert Abs from the FUNCTION menu (or the CATALOG) and put the matrix inside.

Vector App Reference

The Vector app stores two vectors, VctA and VctB, in 2 or 3 dimensions and computes their sum, difference, dot product, cross product, magnitudes, the angle between them and their unit vectors.

Choosing dimensions

Key operation:

Reusing a result — VctAns

Every vector result is kept in VctAns, exactly like MatAns for matrices. Insert it from the CATALOG (in the Calculate app) to carry a vector result straight into the next expression.

Ratio App Reference

The Ratio app finds the missing term X in a proportion A : B = C : D. Choose which position is unknown, enter the three known values, and the calculator solves for X by cross-multiplication.

Choosing the form

Key operation:

Spreadsheet App Reference

The Spreadsheet app is a grid of 5 columns (A–E) × 45 rows. Each cell holds either a number or a formula that begins with = and may reference other cells (A1, B2, …). Formulas recalculate automatically as you edit.

Entering constants

Move the cursor with the arrow keys and type a number to enter a constant into a cell. Press EXE to confirm and drop to the next row. The examples in this chapter build on column A holding the values 1 to 5.

Entering formulas

Start a cell with = to make it a formula. A formula may contain numbers, operators and cell references (A1, B2, …). A reference always tracks the current value of that cell, so the formula recalculates automatically whenever the referenced cell changes.

Relative and absolute references

When a formula is copied or filled to another cell, its references shift with it — these are relative references. A $ locks part of a reference so it does not shift: $A$1 is fully locked, A$1 locks only the row and $A1 only the column.

Range commands — Sum, Min, Max, Mean

The commands Sum(, Min(, Max( and Mean( operate over a block of cells written as a range such as A1:A5. Insert them from the SHEET commands in the CATALOG.

Batch input — Fill Value

To put the same constant into many cells at once, use Fill Value instead of typing it row by row.

The spreadsheet TOOLS menu

Press TOOLS inside the sheet for editing commands that act on the pointed cell or range:

Math Box App Reference

The Math Box app is a set of interactive learning aids: probability experiments and visual number tools. Choose a tool from the menu.

The Math Box menu

Big Number App

The floating calculator (top) and its live extended display with the Big Number explain window (below).

The Big Number app does exact arithmetic on very large whole numbers — hundreds or thousands of digits — and shows the answer in full, never in exponential form. An ordinary calculator would round 1025¹⁰⁰⁰⁰ to a short a × 10ⁿ value; Big Number prints every one of its 30,108 digits.

Press the ⌂ (HOME) key to open the app list and choose Big Number. (Big Number is opened from HOME — not from the blue MODE button, which only switches Normal / Step-by-Step in the Calculate app.) The screen shows the BIG NUMBER banner, an input line, and the result area.

Type whole numbers with the digit keys and combine them with:

• + − × ÷ — add, subtract, multiply, divide;
• ▢^ — a power. The exponent is entered as a raised superscript, so 1025¹⁰⁰⁰⁰ appears just as written; press ▶ to leave the exponent and continue;
• ( ) — parentheses for grouping.

Press EXE to evaluate. Use DEL to delete and AC to clear the line.

After EXE the result area shows a digit count (for example “30,108 digits”) above the number itself. Three chips at the top-right of the display control how the answer is shown:

For a plain whole-number division such as 100000 ÷ 7, a quotient and remainder line (= 14,285 R 5) is shown beneath the decimal value.

Press the ⧉ (cast) button to open the extended display — a large mirror of the calculator screen for a class or projector, marked LIVE DISPLAY. Below it, the explain window restates the expression, the digit count, and the complete grouped result in a scrolling panel, with a one-tap COPY that copies the raw digits. Both refresh automatically after each EXE (shown in the hero at the top of this chapter).

Press the FUNCTION key to insert a function. Each function is inserted as a template with empty ▢ boxes for its arguments — fill the first box, press ▶ (or ▼) to move to the next, and press ▶ once more to leave the closing bracket. You never type a comma.

Worked examples