Calculator

What it does

A simple calculator for everyday sums: shopping, bills, splitting a check, tips, discounts. It follows the order of operations (2 + 3 × 4 = 14), shows the result while you type, keeps a history of the last 30 calculations and has memory keys (M+, M−, MR, MC). The percent key works like a pocket calculator: 200 + 10% = 220.

How to use it

1. Type the calculation with the keys or your keyboard. The result appears as you type.
2. Press = or Enter. The result stays on the display so you can keep calculating with it.
3. Click any line in the history to bring that calculation back.

The arithmetic runs in your browser. Nothing you type is sent anywhere and nothing is stored, so you can use these with real numbers.

Frequently asked questions

How does the % key work?
After + or −, a percentage is taken from the number before it: 200 + 10% = 220 and 200 − 10% = 180. After × or ÷, or on its own, it divides by 100: 50 × 10% = 5.

Why is 2 + 3 × 4 equal to 14 and not 20?
Because multiplication and division are done before addition and subtraction, as in mathematics and in spreadsheets. Old pocket calculators worked from left to right and would show 20. To get 20, type (2 + 3) × 4.

How do the memory keys work?
M+ adds the current result to the memory and M− subtracts it. MR brings the stored number back into the calculation, and MC clears it. The stored number is shown at the top of the display and is kept if you close the page.

Why does 0.1 + 0.2 give exactly 0.3?
Computers store decimals in binary and many programs show 0.30000000000000004. This calculator rounds to 12 significant digits, so you see the answer you expect.

Do I need a scientific calculator?
Only for trigonometry, logarithms, powers, roots and factorials. For those, use the scientific calculator; everything else can be done here.

🔬 Scientific Calculator
% Percentage Calculator
Wikipedia — Calculator