A clean, free online calculator for everyday arithmetic, percentages, and square roots. Works with your mouse, touchscreen, or keyboard.
Recent calculations
- No calculations yet.
Tip: you can type on your keyboard. Use Backspace to delete the last digit and Esc to clear. Results are rounded to 12 significant digits for display.
How to use this calculator
Tap the numbers, choose an operation (÷, ×, −, +), enter the second number, and press =. The small line above the main number shows the calculation in progress, so you always know what you are about to get. Your last five answers are kept under Recent calculations, which makes it easy to compare results or copy a number you worked out a moment ago.
You can also chain operations. For example, typing 12 + 8 × 3 = works from left to right like a pocket calculator: 12 + 8 = 20, then 20 × 3 = 60. If you want the multiplication done first, work it out first (8 × 3 = 24) and then add 12.
What each key does
- ⌫ (Backspace) deletes the last digit you typed. Use it to fix a typo without starting over. For example, if you meant 125 but typed 128, press ⌫ once and then 5.
- AC (All Clear) erases everything and starts a fresh calculation.
- % divides the number on screen by 100. Typing 15 and pressing % gives 0.15, which is handy for working with tips, discounts, and tax rates.
- ± switches the number between positive and negative.
- √ gives the square root of the number on screen. √144 = 12.
- . adds a decimal point.
Keyboard shortcuts
On a computer you don't need the mouse at all. Type numbers with the number keys, use + − * / for the operations, press Enter or = for the answer, Backspace to delete the last digit, Esc to clear, and % for percent.
Everyday examples
- Splitting a bill: a $86.40 dinner shared by 4 people is 86.4 ÷ 4 = 21.6, or $21.60 each.
- Finding a discount: 30% off a $45 jacket. Type 45 × 30 % = and the screen shows 13.5, so you save $13.50. For the sale price, type 45 × 0.7 = to get $31.50.
- Unit price at the store: a 750 g box for $5.25 costs 5.25 ÷ 750 = 0.007 dollars per gram, or 70 cents per 100 g. Compare that with a smaller box to see which is the better deal.
- Checking a room's size: a floor 4.2 m long and 3.5 m wide is 4.2 × 3.5 = 14.7 square metres.
Common questions
Why does the screen say "Error"?
Two things cause an error: dividing by zero, and taking the square root of a negative number. Neither has an ordinary real-number answer. Press AC, ⌫, or any number key to continue.
Why can't I backspace an answer?
Backspace edits the number you are typing. Once you press =, the result is a finished answer, so ⌫ leaves it alone. Simply start typing a new number, or press an operation key to keep calculating with the result.
How accurate are the results?
Answers are shown to 12 significant digits, which is more than enough for everyday use. Like most computer calculators, it stores numbers in binary, so a very long decimal may be rounded in the last place.
More tools for everyday math
- Percentage Calculator – percent of a number, percent change, and more
- Tip Calculator – tips and bill splitting in one step
- Conversion Calculator – metric and imperial units
- Graphing Calculator – see equations drawn as graphs