What this calculator does
This is the ordinary calculator: type a sum, get an answer. The difference from the plastic one on your desk is that it reads the whole expression at once rather than one key at a time, so 12 + 7 × 3 gives 33 and not 57. A desk calculator that has no bracket keys applies each operation the moment you press it, which is why the two disagree.
Because the whole expression is visible, the calculator can also show you how it read it. The "read as" line puts brackets around everything, so if an answer surprises you it is usually obvious why within a second. The step table underneath does the same job more slowly, one operation at a time.
The formula
Operations are resolved in the usual order: brackets first, then functions such as sqrt and factorials, then powers, then multiplication and division left to right, then addition and subtraction left to right. Powers group right to left, so 2^3^2 is 2 to the power 9, which is 512. A minus sign in front binds more loosely than a power, so -2^2 is −4, which is the normal reading in written maths. Put brackets round it if you want 4.
| Term | Meaning |
|---|---|
| + − × ÷ | The four basic operations. You can type * for × and / for ÷. |
| ^ | Raise to a power. 2^10 is 1,024. |
| % | Divides by 100, so 15% × 240 is 36. It does not mean "add a percentage". |
| ! | Factorial. 5! is 1 × 2 × 3 × 4 × 5 = 120. |
| mod | The remainder after division. 10 mod 3 is 1. |
| sqrt cbrt abs | Square root, cube root, absolute value. All take brackets. |
| ln log log2 exp | Natural log, log base 10, log base 2, and e to a power. |
| sin cos tan | Trigonometry, plus asin, acos and atan. The angle setting decides whether these read degrees or radians. |
| pi e phi tau | Constants you can use by name instead of typing the digits. |
The inputs explained
| Field | What to enter |
|---|---|
| Expression | The expression. Brackets, spaces and commas in long numbers are all fine. Writing a number straight against a bracket or a constant multiplies, so 2(3+4) is 14 and 2pi is 6.283. |
| Angles | Only affects the trigonometry functions. Degrees is the usual choice for geometry and angles; radians for calculus and physics. |
When to use it
Working out a bill or an average
Type the whole thing in one go rather than running a total in your head. An average is just (85 + 92 + 78) / 3, and a discount is 240 - 15% × 240. The step table shows the running total if you want to check a figure halfway through.
Checking homework
The "read as" line is the useful part here. Most order-of-operations mistakes are not arithmetic errors, they are bracket errors, and seeing the expression fully bracketed makes the misreading obvious.
Compound growth and powers
Anything that grows by the same percentage repeatedly is a power. A balance growing 10% a year for five years is 1200 × 1.1^5. For the full picture with contributions, use the dedicated exponential growth page.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Why does 2 + 3 × 4 give 14 rather than 20?
Each row contains the same numbers. Only the brackets change, and with them the answer.
| Expression | Result | Read as |
|---|---|---|
| 2 + 3 × 4 | 14 | (2 + (3 × 4)) |
| (2 + 3) × 4 | 20 | ((2 + 3) × 4) |
| 2 + 3 × 4^2 | 50 | (2 + (3 × (4^2))) |
| (2 + 3 × 4)^2 | 196 | ((2 + (3 × 4))^2) |
| -2^2 | -4 | -(2^2) |
| (-2)^2 | 4 | (-2^2) |
What can this calculator do besides the four operations?
A tour of the keys that are not digits. Each is typed exactly as shown.
| Typed | Result | Read as |
|---|---|---|
| sqrt(144) | 12 | sqrt(144) |
| 5! | 120 | 5! |
| 15% × 240 | 36 | (15% × 240) |
| 10 mod 3 | 1 | (10 mod 3) |
| 2^10 | 1,024 | (2^10) |
| log(1000) | 3 | log(1000) |
| sin(30) | 0.5 | sin(30) |
| 2pi | 6.28318531 | (2 × 3.14159265359) |
Questions
Why does my phone calculator give a different answer?
Simple calculators evaluate as you type, applying each operation at the moment you press the next one, so they ignore precedence. This one reads the whole expression first and applies the standard order of operations. For 12 + 7 × 3 the correct answer is 33.
How do I add a percentage to a number?
Multiply rather than add. To add 15%, type 240 × 1.15. To take 15% off, type 240 × 0.85, or 240 - 15% × 240. The % symbol on its own only means "divide by 100", so 240 + 15% comes to 240.15.
Does it do degrees or radians?
Both. The angle setting next to the expression box switches between them and only affects sin, cos, tan and their inverses. Degrees is the default.
What is the biggest number it can handle?
Around 1.8 × 10^308, which is the limit of ordinary double-precision arithmetic. Factorials stop at 170! for the same reason. Beyond about 15 significant digits, results are rounded.
Can I use the keyboard instead of the buttons?
Yes. The expression box is an ordinary text field, so you can type, paste and edit in it. The buttons are there for phones and for the symbols that are awkward to type, such as π and √.
For sums that come up often there is usually a page that shows its working: percentages, percentage change, fraction arithmetic, exponents and roots, logarithms, rounding and significant figures and scientific notation.