Basic Calculator

Left-to-right, not order-of-operations

This calculator evaluates each operation as soon as you press the next operator. It does not apply standard math order-of-operations (multiplication/division before addition/subtraction). That mirrors how a simple four-function calculator has behaved since the earliest pocket models: each button press resolves the pending operation immediately rather than waiting to see what comes next in the expression. If you need proper order-of-operations with parentheses, use the Scientific Calculator instead.

Worked examples

Each example resolves the operation that came before the next operator you press, rather than the operation math class rules would prioritize. In the first example, pressing × after typing 12 + 8 locks in 12 + 8 = 20 immediately, so the following × 2 multiplies that running total rather than multiplying just the 8. Keeping this rule in mind while you type prevents the most common source of unexpected results on this kind of calculator: assuming multiplication always happens before addition when it does not here.

Editing and clearing

The ⌫ key deletes one character from the number you are currently typing, so you can fix a typo without starting the whole expression over. The ± key flips the sign of the current number, useful when you need to subtract a negative value or start a calculation from a negative starting point. C clears everything and resets the display to zero. If a calculation produces an error, most commonly from dividing by zero, the display shows "Error" until you press C or start typing a new number, at which point the calculator resets and accepts fresh input.

Common use cases

This calculator fits the everyday arithmetic most people reach for: splitting a restaurant bill, adding up a shopping list before checkout, converting a quick measurement, or running a rough estimate during a conversation without switching to a spreadsheet. Because it behaves like the physical calculator most people grew up using, there is no learning curve and no risk of a surprising result from operator precedence you were not expecting. For anything involving exponents, roots, trigonometry, or an expression where operator order genuinely matters, the Scientific Calculator handles that correctly with parentheses support.

Keyboard shortcuts

Number keys and + − * / for operators, Enter for equals, Backspace to delete a digit, Esc to clear. Every shortcut works as long as you are not typing inside another input field on the page, so you can keep your hands on the keyboard for an entire sequence of calculations without reaching for the mouse.

Decimal precision

Results round to twelve significant digits, which keeps the display readable while still catching floating-point rounding artifacts that can otherwise creep into arithmetic performed in a browser. Numbers larger than one quadrillion, or a result that overflows that range entirely, show as "Error" rather than an unreadable string of digits, since a number that long stops being useful for the everyday math this calculator is built for anyway.

Chaining several operations

Because each operator resolves the previous step immediately, you can chain as many operations as you want in one continuous sequence without ever pressing equals until the very end. Typing 100 − 20 + 5 × 2, for instance, works through the steps in the order you pressed them: 100 − 20 = 80, then 80 + 5 = 85, then 85 × 2 = 170, and pressing equals confirms that final running total. This running-total behavior is exactly what a receipt tape adding machine or an old desktop calculator does, which is part of why this mode feels familiar even to people who have never thought about the distinction between it and algebraic order-of-operations before.

Is the Basic Calculator free?

Does it show the full calculation I typed?

Does it save calculation history?

Why does 12 + 8 × 2 give 40, not 28?

What happens if I divide by zero?

Are there keyboard shortcuts?