Marketing ROI
Simple Calculator
This is a free simple calculator that runs entirely in your browser — no sign-up, no download, and nothing you type is stored or sent anywhere. Add, subtract, multiply, divide and work out percentages on the keypad below, or just use your keyboard. Whether you arrived looking for a simple calculator, an online calculator or a basic calculator for everyday sums, it is the same trusty tool: type a sum, press =, done.
Your keyboard works too: digits, + − * /, % and Enter. Backspace deletes a digit, Esc clears. The thin line above the display shows the sum you are building.
What order does it do the maths in?
The calculator follows the standard order of operations — multiplication and division before addition and subtraction — so 2 + 3 × 4 = 14, not 20: the 3 × 4 is worked out first. The thin history line above the display always shows the full sum you have built, so you can check the running expression before you trust the answer.
How to use this calculator
Step 1 — type or tap your sum. Use the keypad on screen or your own keyboard; both do exactly the same thing. The number you are typing sits on the big display, and the sum so far runs along the thin line above it. Step 2 — chain as much as you like. There is no need to press = between steps: 12 + 7 − 3 × 2 can be entered as one sum. Step 3 — press = (or Enter). The answer replaces the display and the finished sum stays on the history line. Press an operator to keep calculating from the answer, or start typing digits to begin a new sum.
Two things behave the way a pocket calculator behaves, and are worth knowing:
200 + 15% = 230 — after + or −, the % key takes that percentage of the number before it (15% of 200 is 30)200 × 15% = 30 — after × or ÷, the % key turns the number into a decimal (15 becomes 0.15)2 + 3 × 4 = 14 — × and ÷ are worked out before + and −Mistakes are cheap to fix: CE (or Backspace) deletes the last digit — or, right after an operator, removes that operator so you can pick a different one. C (or Esc) wipes the whole sum. The ± key flips a number between positive and negative; pressed right after an operator it starts a negative number, so 5 + ± 3 = gives 2.
What each key does
| Key | What it does |
|---|---|
| C | Clears everything and starts a new sum (keyboard: Esc) |
| CE | Deletes the last digit you typed; pressed right after an operator, it removes that operator instead (keyboard: Backspace) |
| ± | Makes the number on screen negative, or positive again; pressed right after an operator, it starts a negative number |
| % | Turns the number into a percentage — after + or − it is a percentage of the number before it; after × or ÷, or on its own, it divides the number by 100 |
| + − × ÷ | The four operations. Chain as many as you like in one sum — the calculator keeps the running expression on the line above the display |
| = | Finishes the sum and shows the answer (keyboard: Enter). Press an operator next to keep calculating from the answer, or a digit to start a new sum |
| . | Decimal point, for amounts like 19.99 |
Worked examples
Example 1 — splitting a restaurant bill, tip included
| Keys | 8 6 . 4 0 + 1 5 % = |
| Bill ($86.40) plus a 15% tip | $99.36 |
| Keys | ÷ 4 = |
| Each of the 4 people pays | $24.84 |
The % key did the tip: after +, 15% means 15% of the bill — $12.96 — added on. Then the answer was split four ways without retyping it.
Example 2 — what is 15% of 200?
| Keys | 2 0 0 × 1 5 % = |
| 15% of 200 | 30 |
After ×, the % key turns 15 into 0.15, so the sum is 200 × 0.15. The same two keys answer any ‘percent of a number’ question: a 20% discount on $45 is 4 5 × 2 0 % = → 9.
Example 3 — one sum, done in the right order
| The sum | 3 notebooks at $4, plus a $2 pen |
| Keys | 3 × 4 + 2 = |
| Total | $14 |
Multiplication is worked out before addition, so 3 × 4 = 12 first and the total is $14 — type the whole sum in one go and let the calculator keep the order.
What it does — and what it does not do
This is deliberately a simple calculator, and it is honest about the edges:
- It does: addition, subtraction, multiplication, division, percentages, decimals and negative numbers, in sums as long as you like — with sensible rounding, so 0.1 + 0.2 gives 0.3, not 0.30000000000000004. Dividing by zero shows “Error” rather than a nonsense answer; press any digit to start again.
- It is not a scientific calculator: no powers, square roots, trigonometry or logarithms. To square a number, multiply it by itself (7 × 7 = 49); for real scientific work, use a dedicated scientific calculator.
- No memory keys and no saved history: there are no M+ / MR keys, and nothing is stored between visits — the calculation lives in your browser tab and vanishes when you close it. That is also why nothing you calculate can be seen by anyone else.
- For money percentages, use the specialist tools: a percentage of a price is here, but seller fees, margins and ad returns have rates and formulas of their own — the markup calculator, the break-even calculator and the fee calculators on the homepage already have them built in.
Frequently asked questions
Is this simple calculator free to use?
Yes — completely free, with no sign-up, no account, no download and no limit on how many sums you run. The site is supported by advertising, which is what keeps the tools free.
Does the calculator work with my keyboard?
Yes. Type digits and the decimal point as normal; use + and − for add and subtract, * for multiply and / for divide, % for percent, and Enter or = to finish a sum. Backspace deletes the last digit (the CE key) and Escape clears everything (the C key).
What does the % key do?
It depends on the key before it, the way a pocket calculator behaves. After + or − it takes that percentage of the number before it: 200 + 15% = 230, because 15% of 200 is 30. After × or ÷, or pressed on its own, it divides the number by 100: 200 × 15% = 200 × 0.15 = 30, and 50 % on its own shows 0.5.
Why is 2 + 3 × 4 equal to 14 and not 20?
Because the calculator uses the standard order of operations: multiplication and division are worked out before addition and subtraction, so 3 × 4 = 12 comes first and 2 + 12 = 14. If you want strict left-to-right instead, press = after the first part: 2 + 3 = gives 5, then × 4 = gives 20.
What happens if I divide by zero?
The display shows “Error” — division by zero has no answer, and the calculator will not invent one. Press C, or simply start typing a new sum, and it resets.
Can it do square roots, powers or other scientific functions?
No. This is a basic calculator for everyday arithmetic: the four operations, percentages, decimals and negative numbers. A number can be squared by multiplying it by itself, but for roots, powers, trigonometry or logarithms you need a scientific calculator.
Are my calculations stored or sent anywhere?
No. Every key press is handled inside your own browser — nothing is sent to a server, saved, or shared, and you can prove it by loading this page and using it with your connection switched off.
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