How to use this calculator
This is a standard calculator for everyday sums: shopping totals, bills, recipes, measurements and homework. Tap the keys, or just start typing on your keyboard. The top line shows the calculation as you build it and the big line underneath shows the answer, updated as you go. Press = or Enter to finish, and the calculation moves into your history.
You can keep going from an answer. After pressing =, type an operator such as + or × and the calculator carries on from the result. Type a number instead and it starts a fresh calculation, just like a desk calculator.
| Key | What it does |
|---|---|
| + − × ÷ | Add, subtract, multiply, divide |
| % | Percentage (see below) |
| ( ) | Brackets, worked out first |
| ± | Changes the sign of the last number |
| C | Clears the last number only |
| AC | Clears the whole calculation |
| ⌫ | Deletes one character |
| Ans | Inserts the last answer |
| MC, MR, M+, M− | Memory clear, recall, add, subtract |
Order of operations
The calculator follows the standard order of operations that schools teach as BODMAS (UK, India, Pakistan) or PEMDAS (US): brackets first, then multiplication and division, then addition and subtraction. Operations of the same rank are done from left to right.
This matters because many basic pocket calculators work strictly left to right. On one of those, 2 + 3 × 4 gives 20, because it adds first. If you want the left-to-right answer here, add brackets: (2 + 3) × 4.
You can also type a number straight before a bracket, and it is treated as multiplication: 2(3 + 4) = 14. If you forget to close a bracket at the end, the calculator closes it for you.
How the percent key works
The % key follows the same rules as the calculator on most phones:
| You type | Meaning | Answer |
|---|---|---|
| 200 + 10% | 200 plus 10% of 200 | 220 |
| 200 − 10% | 200 minus 10% of 200 | 180 |
| 50 × 10% | 50 times 0.10 | 5 |
| 50 ÷ 10% | 50 divided by 0.10 | 500 |
| 15% | 15 ÷ 100 | 0.15 |
The rule to remember: after + or −, the percentage is taken of the number before it. That makes adding tax or taking off a discount a one-step job. After × or ÷, the percent sign simply divides by 100.
Percentages also chain. 100 + 10% + 10% is 121, not 120, because the second 10% is taken of 110. That is exactly how compound growth works. For percentage change, reverse percentages and “what percent is X of Y” questions, use the percentage calculator, which shows each formula.
Worked examples
Shopping total with sales tax. Three items at $4.99 and two at $12.50, with 8% sales tax.
39.97 + 8% = 39.97 + 3.1976 = 43.1676 ≈ $43.17
Type 3*4.99+2*12.5 and press =, then type +8% and press = again.
Discount, then tax. A $80 jacket is 25% off, and 7.5% tax is added at the till.
So you pay $64.50. Note that 25% off and then 7.5% on is not the same as 17.5% off: 80 − 17.5% would give $66.
An average, with brackets. Three test scores: 72, 85 and 91.
Without the brackets, 72 + 85 + 91 ÷ 3 divides only the last score and gives 187.33, a common mistake.
Using memory to add up areas. A kitchen is 4.2 m × 3.5 m and a hallway is 3 m × 2.8 m. Type 4.2*3.5, press M+ (memory = 14.7), press AC, type 3*2.8, press M+ (memory = 23.1), then press MR to bring 23.1 m² back. For more shapes, the area calculator handles triangles, circles and more.
Keyboard shortcuts
Everything works without a mouse, on a laptop or with a Bluetooth keyboard on a tablet.
| Key | Action |
|---|---|
| 0–9 and . | Type a number |
| + − * / | Add, subtract, multiply, divide (x also multiplies) |
| % ( ) | Percent and brackets |
| Enter or = | Calculate |
| Backspace | Delete the last character |
| Delete | Clear the last number (C) |
| Esc | Clear everything (AC) |
Keyboard input is ignored while you are typing in another box on the page, so it never gets in the way.
Why some decimals look odd on other calculators
Computers store numbers in binary. Most decimals, such as 0.1, cannot be stored exactly in binary, so a raw computer sum of 0.1 + 0.2 comes out as 0.30000000000000004. This calculator rounds every answer to 15 significant digits, which removes that noise but keeps every digit that is real. You will see 0.3.
Very large and very small answers switch to scientific notation. For example, 123,456,789 × 987,654,321 × 1,000 shows as 1.2193263111e+20, meaning 1.2193263111 × 10²⁰. You can type numbers in this form too: 1.5e3 is 1,500.
Dividing by zero is not allowed, because no number times 0 gives anything other than 0. The calculator tells you instead of showing a confusing “Infinity”.
Tips for accurate answers
- Check the top line before pressing =. It shows exactly what will be calculated, with × and ÷ signs.
- Use C to fix a typo. It removes only the last number, so you do not have to start again.
- Round at the end, not in the middle. Rounding each step can drift by a cent or more on long sums.
- Use ± for negative numbers. It wraps the number in brackets, so 12 × (−5) is calculated correctly.
- Reuse earlier work. Tap the left side of a history line to load the whole calculation, or the result on the right to insert just the answer.
Basic or scientific calculator?
This page covers the four operations, percentages and memory, which is what most people need most of the time. When you need powers, square roots, logarithms or sine and cosine, switch to the scientific calculator. For exact fractions such as 2/3 + 3/4, the fraction calculator gives 17/12 instead of a rounded decimal. To see every step of a division by hand, try the long division calculator.
Privacy
Every calculation runs in your browser. Nothing you type is sent anywhere. Your history is stored only in this browser so it is there next time, and Clear history removes it.