Basic Calculator

A free, fast online basic calculator for everyday maths. Add, subtract, multiply, divide, work out percentages, and chain calculations together — right in your browser, with no sign-up required.

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How to use the basic calculator

  1. Enter a number by tapping the digit keys, or type it on your keyboard.
  2. Choose an operation: +, −, ×, or ÷.
  3. Enter the second number, then press = to see the result.
  4. Keep going — the result becomes the start of your next calculation, so you can chain as many steps together as you like.
  5. Press AC to start over, or DEL to fix a mistyped digit.

How it works

This calculator follows the standard left-to-right calculator model most people already know from a physical calculator: each operator is applied as soon as the next one is pressed, so 4 + 3 × 2 is worked out as (4 + 3) × 2 = 14, not using algebraic order of operations. Percentages follow the same convention as most calculators: with + or −, % works out a percentage of the first number and you still press = to combine them, so 200 + 10% = gives 220. With × or ÷, % gives you the answer straight away — 200 × 10% shows 20 without needing a separate = press.

Behind the scenes, results are rounded to remove the tiny floating-point rounding errors that can appear in raw JavaScript maths, so 0.1 + 0.2 shows a clean 0.3, not 0.30000000000000004, while keeping enough precision for everyday calculations. Like any calculator built on standard double-precision numbers, extremely large results beyond roughly 15–16 digits are shown as an approximation rather than an exact figure. Pressing = again without entering a new number repeats the last step, so 5 + 3 = = = counts up by 3 each time: 11, 14, 17.

A simple example

Say you’re splitting a bill of 68.40 three ways. Enter 68.4, press ÷, enter 3, then press =. The calculator shows 22.8 — each person’s share.

Frequently asked questions

Is this basic calculator free to use?
Yes. Calqeno’s basic calculator is completely free, works in your browser, and doesn’t require an account.
Can this calculator handle percentages?
Yes. With + or −, % works out a percentage of the first number and you press = to combine them (200 + 10% = 220). With × or ÷, % gives you the answer straight away (200 × 10% = 20).
Does it support decimal numbers?
Yes. Use the decimal point key to enter numbers with decimals. Common floating-point rounding glitches are cleaned up automatically.
What happens if I divide by zero?
The calculator shows “Cannot divide by zero” and lets you keep calculating — nothing gets stuck or breaks.
Can I use my keyboard instead of clicking?
Yes. Number keys, +, -, *, /, ., %, Enter, Backspace and Escape all work like their on-screen equivalents.
Does the calculator save my calculations?
Your recent calculations appear in the History panel for the current visit only. Nothing is stored after you leave the page.

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