Maths Calculator

What this calculator does

Sometimes you just need to work something out. This is a plain, quick calculator for everyday sums: add, subtract, multiply, divide, throw in some brackets or a decimal, and get the answer. No frills, and it runs right here in the browser.

You can tap the buttons or, if your hands are already on the keys, type the whole thing out and hit Enter.

Using the calculator

1. Build your sum with the number and operator buttons: +, −, ×, ÷, brackets, a decimal point, and %.
2. Press = to get the answer.
3. Press C to clear and start again.

Brackets are there for a reason, and the next section explains when you actually need them.

The one thing to know: order of operations

A calculator does not simply work left to right, and this catches people out. It follows the standard order of operations: anything in brackets first, then multiplication and division, and only then addition and subtraction.

So 2 + 3 × 4 is not 20. The multiplication happens before the addition, giving 3 × 4 = 12, then 2 + 12 = 14. If you actually wanted the adding to come first, that is what the brackets are for: (2 + 3) × 4 forces the 2 + 3, then multiplies by 4, giving 20. When in doubt, add brackets. They cost nothing and remove all doubt about what gets done first.

A worked example

Say you type 2 + 3 × 4 and press equals.

1. The calculator looks for multiplication and division first: 3 × 4 = 12.
2. Then it does the addition: 2 + 12 = 14.

Change it to (2 + 3) × 4 and the bracket goes first: 2 + 3 = 5, then 5 × 4 = 20. Same numbers, different answer, all down to what the brackets tell it to do first.

Keyboard shortcuts

You do not have to click. The calculator takes keyboard input, so you can type the digits and the + - * / operators straight in. Enter works the same as equals, Backspace deletes the last thing you typed, and Delete clears the lot. For longer sums it is far quicker than reaching for the buttons.

If you would rather have this same calculator filling the whole screen, bigger and easier to read across a room, the full-screen calculator is the same thing in a full-screen layout.

Questions people ask

Why does 2 + 3 × 4 give 14, not 20?

Because multiplication is done before addition. The calculator works out 3 × 4 = 12 first, then adds the 2, giving 14. Use brackets if you want the addition to happen first.

When do I need brackets?

Whenever you want a part of the sum done first, out of the usual order. (2 + 3) × 4 forces the addition ahead of the multiplication.

Can I use my keyboard?

Yes. Type the digits and the + - * / keys, use Enter for equals, Backspace to delete, and Delete to clear.

Does it handle decimals?

Yes, use the decimal point button or key as normal.

Is there a bigger version?

Yes, the full-screen calculator is the same calculator laid out to fill the whole screen, handy when you want it larger or distraction-free.

References

A note on where this comes from. The calculator follows the standard order of operations, the widely agreed convention that brackets are evaluated first, then multiplication and division, then addition and subtraction, so that a written expression has one clear meaning. For further reading, see Order of operations.

1. The order of operations convention, resolving the sequence in which an expression is evaluated.