Basic Calculator guide
Basic Calculator: A Simple Online Calculator
Use our free basic calculator to add, subtract, multiply and divide, with percentages, brackets and keyboard support.
By the AllCalculator editorial teamUpdated 16 October 20261 min read
Sometimes you just need to add up a few numbers. Our Basic Calculator is a simple, four-function calculator with big buttons that works on any phone, tablet or computer.
How to use the calculator (Basic Calculator)
- Tap the numbers and operators, or type them on your keyboard.
- Press = or Enter to see the answer.
- Press C or Esc to clear, and ⌫ or Backspace to delete the last digit.
The answer updates as you type, so you can see the result before you press equals.
The keys
| Key | What it does |
|---|---|
| + − × ÷ | Add, subtract, multiply and divide |
| % | Turns the number before it into a percentage, so 50% is 0.5 |
| ± | Changes the sign of the last number |
| C | Clears everything |
| ⌫ | Deletes the last character |
Order of operations
The calculator follows BIDMAS: brackets first, then powers, then division and multiplication, then addition and subtraction. So 2 + 3 × 4 = 14, not 20. Type brackets on your keyboard if you need them, like (2 + 3) × 4 = 20.
A worked example
Type 12 × 7 and press equals to get 84. Press + 16 = to carry on from the answer and get 100.
Frequently asked questions
How do I work out a percentage of a number?
Multiply by the percentage: 200 × 15% gives 30. For percentage changes and increases, use our Percent Change Calculator.
Can I use powers and square roots?
Use our Scientific Calculator for powers, roots, trig and logs.
Why does 0.1 + 0.2 show 0.3?
Computers store decimals in binary, which can cause tiny rounding errors. The calculator rounds the display so you see the answer you'd expect.
Sources and further reading
Links open official and independent websites in a new tab.
This guide is general information to help you understand your options. It isn't financial, tax, legal or building advice and doesn't take your personal circumstances into account. Figures were checked when the guide was last updated and can change, so confirm anything important with GOV.UK, HMRC, a regulated adviser or a qualified tradesperson.