Basic Calculator Guide

What This Calculator Does

The Basic Calculator is designed for one quick step at a time, not for entering a long formula. It provides:

• addition +, subtraction −, multiplication ×, and division ÷;
• decimal input and sign change ±;
• square root √ for non-negative real values;
• MC, MR, M+, and M- memory keys;
• recent calculation history, keyboard control, sharing of the current memory value, and fullscreen mode.

It is a good fit for shopping totals, bill checks, budgets, homework verification, and short chained calculations. It is not a scientific calculator or a parenthesized expression parser with variables and functions.

When to Use It

• You want to add or split several prices quickly.
• You need a few multiplication, division, or running-total steps and a temporary value.
• You want to review the most recent ten completed calculations.
• You prefer keyboard input or a fullscreen, large-button layout.
• You only need square root or sign change, not advanced mathematical functions.

Inputs Explained

Numbers, Decimals, and Sign

Use the number keys to enter an integer or decimal. A number accepts one decimal point. The ± key toggles the sign of the current display; zero is not changed into negative zero.

Arithmetic Operations

Use the sequence “number → operator → next number → equals.” The operators are +, −, ×, and ÷. You can continue from the previous result, but the page does not accept a free-text expression.

Square Root

√ applies the real square-root function to the current non-negative display, such as √9=3. A negative display shows Error rather than returning a complex number.

Memory Keys

• MC: clear the memory value.
• MR: recall the memory value to the display.
• M+: add the current display to memory.
• M-: subtract the current display from memory.

The memory indicator appears near the display when memory is non-zero. It is one reusable intermediate value, separate from history.

History, Keyboard, and Fullscreen

Completed equals calculations and square-root results are saved in recent history, up to 10 entries. Clicking a history entry restores its result to the display. Keyboard control supports digits, + - * /, the decimal point, Enter/=, Esc, and Backspace. Fullscreen hides the page header and footer so the keypad gets more room.

How the Calculation Works

The page uses calculator-style left-to-right chaining rather than expression-precedence parsing. For example:

[ 12+7\times2\quad\text{is evaluated as }12+7=19\text{, then }19\times2=38 ]

Each intermediate result is passed into the next operation. After normal arithmetic, roundFloat keeps about 10 decimal places to reduce familiar JavaScript display noise such as 0.1+0.2. Division uses ordinary JavaScript numeric division, but a zero divisor shows Error. Square root uses the real-number branch and rejects negative inputs.

History, memory, and the last result use localStorage in the current browser. The share action puts only the memory value in the URL; it does not encode the display, full calculation chain, or history.

Example

A running total

Press 12, +, 7, and =:

[ 12+7=19 ]

The display shows 19, and the completed calculation is added to history.

Left-to-right chaining

Press 12, +, 7, ×, 2, and =:

The page first evaluates 12+7=19, then 19×2=38. If the intended mathematical answer is 12+7×2=26, split the work into separate steps or use the Mathematical Expression Calculator.

Square root and memory

Enter 9, press √ to get 3, then press M+. After entering another value, press MR to restore 3. Memory and history can be managed independently.

Decimal display

Use the key sequence for 0.1+0.2. The page displays a rounded result around 0.3 instead of exposing the familiar long binary floating-point artifact. It is still JavaScript Number arithmetic, not an arbitrary-precision decimal system.

How to Understand the Result

• Display: the current input, intermediate value, or final result.
• Expression hint: the short pending step, such as 12 +, while the calculator waits for another number.
• Memory indicator: the stored intermediate number when memory is non-zero.
• History: the last 10 completed equals or square-root results; click one to restore it.
• Error: usually division by zero or a real square root of a negative number; clear the display and try again.

Treat the output as a numeric result for the current key sequence. It does not infer units, currencies, tax rates, percentages, or the meaning of a formula.

Common Mistakes

• Expecting 12+7×2 to produce 26; this keypad sequence produces 38.
• Trying to use the calculator as a parentheses, power, function, or variable parser.
• Continuing after division by zero without pressing Clear.
• Expecting a complex result from the square root of a negative number.
• Confusing one MR memory value with the list of history entries.
• Assuming Clear also deletes memory and history; those are separate controls.

FAQ

Does the Basic Calculator have a percent key?

No. It has no dedicated percentage mode. Use the Percentage Calculator for percentages, discounts, tax, tips, and change rates.

What is the difference between chaining and a full formula?

Chaining evaluates one current operation at a time from left to right. A full formula may require parentheses, precedence, and functions, so use an expression or scientific calculator for that work.

How many history entries are kept?

The page keeps the latest 10 entries in browser localStorage. Clearing history does not automatically clear the memory value.

Does the share link expose my history?

No. The current share action puts only the memory number in the URL; history, display contents, and key steps are not included. Avoid leaving sensitive numbers on a shared device.

Is the result arbitrary precision?

No. Results use JavaScript Number and roughly 10-decimal rounding after normal operations. Very large values or strict fixed-decimal work need a specialized tool.

Notes

This page focuses on non-symbolic numeric tasks: four arithmetic operations, square root, sign change, memory, history, and keyboard input. It does not provide parenthesized or precedence-aware expressions, variables, functions, trigonometry, logarithms, powers, a dedicated percentage mode, unit conversion, complex numbers, arbitrary precision, statistics, or financial rules.

Results are affected by JavaScript Number, floating-point rounding, and display precision; division by zero and negative square roots enter an error state. For broader work, use the Mathematical Expression Calculator, Scientific Calculator, or Percentage Calculator.