Basic Calculator
- Updated
- Formula shown
- Free, no sign-up
Expression: 0
Result: 0
Keyboard: digits, . + − * / %, Enter for =, Backspace, Esc to clear all, Delete to clear the entry and F9 for ±.
Results
Result 0
Follows the order of operations: × and ÷ before + and −, so 2 + 3 × 4 = 14.
How to use the basic calculator
- Tap the keys or type on your keyboard. The top line of the display shows what you have entered; the large line shows the answer so far.
- Press = (or Enter) to finish. Keep pressing operators to carry on from the answer, or type a digit to start a new sum.
- CE clears only the number you are typing, C clears everything, and the backspace key in the display removes the last character.
- ± changes the sign of the current number, so you can enter 5 − (−3) without brackets.
- Use M+ to add the current answer to memory, M− to subtract it, MR to bring it back and MC to clear it. An “M” in the display means something is stored.
Order of operations and the percent key
2. Addition and subtraction, left to right
A + B% = A + A × B ÷ 100 · A − B% = A − A × B ÷ 100
A × B% = A × B ÷ 100 · A ÷ B% = A ÷ (B ÷ 100)
This calculator evaluates the whole line you type, the way a phone calculator or spreadsheet does. Multiplication and division are done before addition and subtraction, and operations of the same rank are done from left to right. Some cheap desk calculators work differently and apply each operator as soon as you press it, so 2 + 3 × 4 gives 20 on those but 14 here, which is the mathematically correct answer.
The percent key follows the familiar pocket-calculator rule. After a plus or minus, B% means “B percent of the number before it”, which is exactly what you want for adding tax or taking off a discount. After × or ÷, and on its own, B% simply means B ÷ 100.
Worked example: a receipt with sales tax
You buy three notebooks at $4.25 and two pens at $1.80, and sales tax is 8%. Type 3 × 4.25 + 2 × 1.80 = to get the subtotal of
$16.35. Then press + 8 % =. The calculator adds 8% of 16.35, which is 1.308, and shows
17.658, so the bill comes to about $17.66. Press M+ to keep that total in memory while you
work out the next one.
Order of operations examples
| You type | Result | Why |
|---|---|---|
| 2 + 3 × 4 | 14 | × first: 2 + 12 |
| 12 ÷ 4 × 3 | 9 | Left to right: 3 × 3 |
| 10 − 4 − 3 | 3 | Left to right: 6 − 3 |
| 7 − 2 × 3 + 1 | 2 | × first: 7 − 6 + 1 |
| 100 ÷ 8 ÷ 5 | 2.5 | Left to right: 12.5 ÷ 5 |
What the % key does
| You type | Result | Meaning |
|---|---|---|
| 200 + 15 % | 230 | Add 15% of 200 |
| 200 − 15 % | 170 | Take 15% of 200 off |
| 200 × 15 % | 30 | 15% of 200 |
| 200 ÷ 15 % | 1,333.3333 | 200 is 15% of what? |
| 15 % | 0.15 | 15 as a decimal |
Keyboard shortcuts
- 0–9 and . enter numbers (a comma also works as the decimal point).
- + − * / are the four operations; x also multiplies, and % is percent.
- Enter or = gives the answer, Backspace deletes, Esc clears all, Delete clears the entry and F9 changes the sign.
Tips and common mistakes
- Check long sums twice. The top line keeps the whole calculation visible, so you can spot a mistyped digit before pressing =.
- Watch rounding. Answers show up to 12 significant digits. 1 ÷ 3 appears as 0.333333333333, and very large or small answers switch to E-notation, where 1.5E12 means 1.5 × 10¹².
- Dividing by zero has no answer. The calculator says so instead of showing a number, and keeps your entry so you can fix it.
- A percent change is not reversible by the same percent. 200 + 15% is 230, but 230 − 15% is 195.5. Use the percentage calculator for percentage change and difference.
- Need brackets, powers or trigonometry? Switch to the scientific calculator. For exact sums with fractions, use the fraction calculator.
Frequently asked questions
Does this calculator follow the order of operations?
Yes. Multiplication and division are done before addition and subtraction, left to right, so 2 + 3 × 4 = 14. Some simple desk calculators work through each key as you press it and would show 20.
How does the percent key work?
After + or −, B% means B percent of the number before it: 200 + 15% = 230 and 200 − 15% = 170. After × or ÷, and on its own, B% means B ÷ 100: 200 × 15% = 30.
What is the difference between C and CE?
CE (clear entry) removes only the number you are typing, so you can retype it without losing the rest of the calculation. C clears the whole calculation. Neither clears the memory; use MC for that.
How do I use the memory keys?
M+ adds the current answer to memory and M− subtracts it, MR puts the stored value into your calculation and MC sets it back to zero. An M in the display shows that a value is stored.
Why does 1 ÷ 3 show 0.333333333333?
One third has a never-ending decimal, so the calculator shows the first 12 significant digits. Very large or very small answers switch to E-notation: 1.5E12 means 1.5 × 10¹², or 1,500,000,000,000.