Basic Calculator
Add, subtract, multiply and divide with percent, square root and memory keys, and see every step in the order it was worked out.
Multiplication and division come before addition and subtraction, so 3 × 4 is worked out first.
Calculation tape
Press = or Enter to save a calculation here. Tap a saved line to use its answer again.
Your calculation
Each operation in the order the calculator worked it out.
- Multiply: 3 × 4 = 12
- Add: 2 + 12 = 14
How other calculators read this
The same keys can give different answers. Brackets remove any doubt.
| Rule | Used by | Answer |
|---|---|---|
| Order of operations | This calculator, scientific calculators, spreadsheets | Same as the answer |
| Left to right, one key at a time | Some basic pocket calculators | 20 |
| Percent read as ÷ 100 | Spreadsheets such as Excel | Same |
| Minus sign before powers | Excel | Same |
Answers show up to 12 significant digits. Computers store numbers in binary, so tiny errors such as 0.1 + 0.2 = 0.30000000000000004 are rounded away.
What This Basic Calculator Does
This basic calculator handles the everyday arithmetic you would do on a pocket calculator: addition, subtraction, multiplication and division, plus a percent key, square and square root keys, powers, brackets and four memory keys. You can tap the keys on screen or type a whole calculation with your keyboard, such as 12.50 × 3 + 8.75 × 2.
Unlike a pocket calculator, it shows its working. The answer appears first, then a list of each operation in the order it was done, so you can check that 2 + 3 × 4 really gives 14. A comparison table shows what a left to right pocket calculator or a spreadsheet would give for the same keys, which explains most cases where two calculators disagree.
Each answer you confirm with = or Enter is saved to a calculation tape, so you can look back at earlier results, reuse them or copy the whole list. The tape and memory stay in your browser when you reload the page.
How to Use the Basic Calculator
- Enter a calculation. Tap the keys or type into the display. You can type a full expression at once, for example (72 + 85 + 91) ÷ 3. The symbols * and / work for multiplication and division, and commas in numbers such as 1,234,567 are ignored.
- Watch the preview. The answer under the display updates as you type, so you can see the result before you finish.
- Press = or Enter. This saves the calculation to the tape. Type an operator next to keep working with the answer, or type a digit to start a new calculation.
- Read the results. The large number is the answer. The line below it says which rule decided the result, and the steps list shows every operation with your numbers.
If you leave a bracket open, the calculator closes it for you at the end and says so in a chip next to the answer. If an expression cannot be calculated, such as 5 ÷ 0, a short message explains why instead of showing a wrong number.
Calculator keys and keyboard shortcuts
| Key | What it does | Keyboard |
|---|---|---|
| + − × ÷ | Add, subtract, multiply, divide | + − * / |
| % | Percent: divides by 100, or a percent of the number before it after + or − | % |
| √ | Square root of the number or bracket after it | √ or sqrt |
| x² | Squares the number or bracket before it | ² or ^2 |
| ^ | Raises to a power, such as 2^10 | ^ |
| ( ) | Brackets, worked out first | ( ) |
| ± | Changes the sign of the last number | Type a minus sign |
| ⌫ and C | Delete one character, or clear everything | Backspace, Escape |
| = | Shows the answer and saves it to the tape | Enter |
| MC MR M+ M− | Memory clear, recall, add, subtract | Keys only |
Order of Operations (PEMDAS and BODMAS)
When an expression has more than one operation, the order of operations decides which comes first. OpenStax Prealgebra lists the order as parentheses, then exponents, then multiplication and division from left to right, then addition and subtraction from left to right. PEMDAS and BODMAS are memory aids for the same rule.
Multiplication does not always come before division. They have equal rank, so you work them from left to right, which is why 8 ÷ 2 is done before 2 × 3 in the second example. The same applies to addition and subtraction.
Why Some Calculators Give a Different Answer
Some basic pocket calculators apply each operation as soon as you press the next operator key. Typing 2 + 3 × 4 on one of these gives 5 after the × key and 20 at the end, because the addition was finished before the multiplication was entered.
The second example above, 20 − 8 ÷ 2 × 3, gives 18 on a left to right calculator: 20 − 8 = 12, then 12 ÷ 2 = 6, then 6 × 3 = 18. The correct answer under the order of operations is 8.
The comparison table under the results shows the left to right answer for whatever you type, so you can see at once whether the reading matters.
How the Percent Key Works
Percent means per 100, so 15% is 15 ÷ 100 = 0.15. On its own or after × and ÷, the % key on this calculator does exactly that. After + or −, it works like most pocket calculators and takes that percent of the number before it, which is what you want for tax, tips and discounts.
| You type | Answer | How it is read |
|---|---|---|
| 15% | 0.15 | 15 ÷ 100 |
| 80 × 15% | 12 | 15% of 80 |
| 50 ÷ 25% | 200 | 50 ÷ 0.25 |
| 49.99 + 8.25% | 54.114175 | 49.99 plus 8.25% of 49.99 (4.124175) |
| 120 − 15% | 102 | 120 minus 15% of 120 (18) |
| 100 + 10% + 10% | 121 | 110, then 10% of 110 added |
The last row shows that two percent increases in a row compound. Adding 10% twice gives 121, not 120, because the second 10% is taken from 110. The same happens with discounts: 15% off and then another 10% off is 23.5% off in total, not 25%.
Squares, Square Roots and Powers
The x² key multiplies a number by itself: 5² = 5 × 5 = 25. The √ key finds the number that gives the value when multiplied by itself: √144 = 12, because 12 × 12 = 144. Put an expression in brackets after √ to take its root: √(9 + 16) = √25 = 5.
Most square roots are not whole numbers. √2 = 1.41421356237 to 12 significant digits. For other powers use ^: 2^10 = 1,024. Powers and roots are worked out before multiplication, so √144 + 5² = 12 + 25 = 37.
Using the Memory Keys and the Tape
Memory holds one number while you work on something else. M+ adds the current answer to memory, M− subtracts it, MR puts the stored value into your calculation and MC resets memory to 0.
To total a receipt with 3 items at 12.50 and 2 at 8.75, calculate 12.50 × 3 = 37.5 and press M+. Then calculate 8.75 × 2 = 17.5 and press M+. Press MR and the display shows 55. You can also type 12.50 × 3 + 8.75 × 2 in one go, since multiplication comes first.
The tape keeps your last 20 calculations. Tap any line to bring its answer back into the display, or use Copy tape to paste the list into a note or email.
Rounding and Display Precision
JavaScript, which runs this calculator, stores numbers as IEEE 754 double precision values. MDN describes this format as precise to about 15 to 17 significant digits. To hide the tiny binary errors this causes, answers are shown to 12 significant digits, so 2 ÷ 3 shows 0.666666666667 and 0.1 + 0.2 shows 0.3 rather than 0.30000000000000004.
The full value is kept between steps, so 1 ÷ 3 × 3 gives exactly 1. Answers of 1,000,000,000,000,000 or more, or very small answers below 0.000001, switch to scientific notation, such as 1.5 × 10¹⁸.
Round money only once, at the end. If a pack of 12 costs 4.99, then 4.99 ÷ 12 = 0.415833333333, which is 0.42 per item to the cent. The rounded tiles in the results show the answer to 2 decimal places and to the nearest whole number, and a fraction tile shows answers such as 248/3 when the decimal repeats.
Everyday Calculations
Split a bill
Divide the total by the number of people: 86.40 ÷ 4 = 21.60 each. To add an 18% tip first, type 86.40 + 18% = 101.952, then ÷ 4 = 25.488, or 25.49 each. The tip alone is 86.40 × 18% = 15.552, about 15.55.
Compare unit prices
Divide each price by its size. A 16 ounce jar at 3.49 costs 3.49 ÷ 16 = 0.218125 per ounce, and a 32 ounce jar at 5.99 costs 5.99 ÷ 32 = 0.1871875 per ounce, so the larger jar is cheaper per ounce.
Weekly pay and averages
Multiply your hourly rate by hours worked: 18.50 × 37.5 = 693.75. To average three test scores, add them in brackets and divide: (72 + 85 + 91) ÷ 3 = 82.6666666667, or about 82.67. Without brackets, 72 + 85 + 91 ÷ 3 divides only the last score and gives 187.333333333.
Common Mistakes
- Leaving out brackets. 72 + 85 + 91 ÷ 3 is not an average. Put the sum in brackets before dividing.
- Squaring a negative without brackets. −3² is −9. Write (−3)² for 9.
- Rounding too early. Rounding 4.124175 to 4.12 before adding gives the same total here, but repeated early rounding across many lines can shift the final cents.
- Expecting percent to work like a spreadsheet. 120 − 15% is 102 here and 119.85 in Excel.
- Adding percents. Two 10% increases make 21%, not 20%.
Related Calculations
For trigonometry, logarithms and more functions, use the Scientific Calculator. To find what percent one number is of another or a percent change, use the Percent Calculator.
For exact answers with fractions such as 2/3 + 1/4, use the Fraction Calculator. The Tip Calculator and Sales Tax Calculator handle bills and receipts, the Rounding Calculator rounds to any place and the Average Calculator finds the mean of a whole list.
Frequently Asked Questions
How do you calculate a percentage on a calculator?
To find a percent of a number, multiply by the percent: 86.40 × 18% = 15.552, so an 18% tip on 86.40 is about 15.55. To add a percent, type the number, then plus and the percent: 49.99 + 8.25% = 54.114175, or 54.11. To take a percent off, use minus: 120 − 15% = 102. On its own, the % key divides by 100, so 15% is 0.15. After plus or minus it means that percent of the number before it.
What is the order of operations on a calculator?
Work out brackets first, then powers and roots, then multiplication and division from left to right, then addition and subtraction from left to right. So 2 + 3 × 4 = 2 + 12 = 14, not 20. In 20 − 8 ÷ 2 × 3, divide first (8 ÷ 2 = 4), multiply next (4 × 3 = 12), then subtract: 20 − 12 = 8. To force a different order, use brackets: (2 + 3) × 4 = 20. This calculator follows these rules and lists each step in the order it was done.
Why does my calculator give a different answer?
Calculators differ in three common ways. Some basic calculators apply each operation as soon as you press the next key, so 2 + 3 × 4 gives 20 instead of 14. Spreadsheets read a percent sign as division by 100, so 49.99 + 8.25% gives 50.0725 rather than 54.114175. Excel also applies a minus sign before powers, so −3^2 is 9 in Excel but −9 under the usual math rule. The comparison table under the results shows how your expression reads in each style.
How do you use the memory buttons on a calculator?
M+ adds the current result to memory, M− subtracts it, MR recalls the stored value into the calculation and MC clears memory to 0. To total two items on a receipt, calculate 12.50 × 3 = 37.5 and press M+, then calculate 8.75 × 2 = 17.5 and press M+ again. Press MR and the display shows 55, the total of both lines. On this page the memory value is shown in a results tile and is kept when you reload the page.
How do you add sales tax on a calculator?
Type the price, press plus, then type the tax rate and press %. For a 49.99 item with 8.25% tax, 49.99 + 8.25% = 54.114175, which rounds to 54.11. You get the same result by multiplying by 1 plus the rate as a decimal: 49.99 × 1.0825 = 54.114175. To see the tax alone, multiply instead: 49.99 × 8.25% = 4.124175, or 4.12. Round money only at the end, after the last step, so small rounding errors do not add up.
How do you find a square root on a calculator?
Press √ and then type the number, or put an expression in brackets after it. √144 = 12, because 12 × 12 = 144, and √(9 + 16) = √25 = 5. Most square roots are not whole numbers: √2 = 1.41421356237 to 12 significant digits. The x² key does the opposite and multiplies a number by itself, so 5² = 25. A negative number has no real square root, so √(−4) shows a message instead of an answer.
Sources & References
- OpenStax. Prealgebra 2e, 2.1 Use the Language of Algebra (order of operations: parentheses, exponents, multiplication and division left to right, addition and subtraction left to right). openstax.org
- OpenStax. Prealgebra 2e, 6.1 Understand Percent (percent means per 100; converting percents to decimals). openstax.org
- Microsoft Support. Calculation operators and precedence in Excel (percent operator, negation applied before exponentiation, operator precedence in spreadsheets). support.microsoft.com
- MDN Web Docs. Number (IEEE 754 double precision format, about 15 to 17 significant digits). developer.mozilla.org
Results are for educational and everyday use. Every number on this page was recomputed with the same code the calculator uses. Methodology reviewed: 2026.