About Factorial Calculator
This calculator finds factorials. Type 5 then the x! key, or write 5!, and you get 120. It opens on 10!/(6!×4!), which is the number of ways to choose 4 items from 10. It is free, needs no sign-up and runs in your browser, so nothing you enter is uploaded.
The factorial of n is n × (n − 1) × … × 1, and 0! is defined as 1. It grows fast: 10! is 3,628,800 and 20! is already about 2.4 × 10¹⁸. Factorial works up to 170! in this calculator; 171! is larger than any number it can hold and reports an error.
Dividing factorials keeps numbers small: write 10!/(6!×4!) rather than computing each large factorial separately. The same quotient is available directly as nCr(10,4).
How to use Factorial Calculator
- Choose the angle unit first: DEG for degrees, RAD for radians or GRAD for gradians.
- Type the expression with the keyboard, or tap the keys. On a phone the scientific keys sit behind the "Show scientific keys" button.
- Read the live answer under the expression. Press Enter or = to keep it in the history and store it as Ans.
- Press 2nd for inverse functions, then a function key such as sin to get sin⁻¹.
- Use nCr(10,3), nPr(5,2) and root(27,3) with a comma between the numbers, or write 10 nCr 3.
- Tap a history entry to load its expression again, or Use to paste its result into the line you are writing.
Features
- Degrees, radians and gradians, with exact results at the common angles: sin(30°) is 0.5 and sin(180°) is 0, not 1.2e-16.
- Sin, cos, tan, their inverses, sinh, cosh, tanh and their inverses.
- Natural log, base-10 log and log with any base, written log(8,2).
- Squares, cubes, any power, square root, cube root and nth root, factorial, reciprocal and absolute value.
- Combinations nCr and permutations nPr, as functions or in the infix form 10 nCr 3.
- Percent, modulo, E notation (1.5E3), constants π and e, and Ans for the previous answer.
- Memory keys MC, MR, M+, M− and MS.
- A live typeset preview of the input, and a result display in large tabular figures.
- Optional fraction form of the result: 0.625 shown as 5/8 as well.
- History with click-to-reuse, a clear button and a copy button for the result.
Factorial formula
n factorial is the product of the whole numbers from 1 to n.
n! = n × (n − 1) × … × 2 × 1
0! = 1Worked examples
5! gives 120
5 × 4 × 3 × 2 × 1.
10! gives 3628800
3,628,800.
10!/(6!×4!) gives 210
Choose 4 from 10.
20! gives 2.43290200818E18
Large factorials switch to E notation.
Privacy: how it works
- Every calculation runs in your browser tab. The history is saved in this browser only (local storage) and is never sent to Ulkaa or anyone else. Clear it with one button, or clear your browser data.
Tips
- log means base 10 and ln means natural log. Use log(x,b) for any other base.
- Percent turns the number before it into a hundredth, so 200×10% is 20. Write mod for a remainder: 10 mod 3 is 1.
- Factorial works for whole numbers up to 170 and gives an error beyond, because the result no longer fits in a number.
- If the keypad is in the way on a phone, tap the keyboard button beside the expression to type with the device keyboard.
- tan(90°) has no value, and the calculator says so instead of showing a huge number.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial and no credit card. Ulkaa Tool does the work with your own device, so there is no server bill to pass on to you.
Do I need an account?
No. There is no sign-up and no login. Open the page and use it. An Ulkaa account is not needed for anything on this tool.
Does it run in my browser?
Yes. Your calculations are processed by code running in your browser tab, on your own device.
Is my data uploaded?
No. Your calculations are never sent to Ulkaa or to anyone else. You can check this yourself by watching the Network tab in your browser developer tools while you use the tool.
What is 0 factorial?
By definition 0! is 1. It keeps formulas such as nCr(n, 0) = 1 consistent.
What is the largest factorial this calculator can do?
170!. The next one, 171!, is bigger than the largest number the calculator can store, so it reports an error.
More Scientific Calculator pages
- Scientific CalculatorA full scientific keypad with degrees, radians and gradians, memory, history and a live formula preview.
- Scientific Calculator in Degree ModeSin, cos and tan in degrees, with exact answers at the common angles.
- Scientific Calculator in Radian ModeTrigonometry in radians, with π as a key and inverse functions that return radians.
- Scientific Calculator in Gradian ModeTrigonometry in gradians, also called gons or grades, where a full turn is 400.
- Scientific Calculator With Fraction ResultsType a calculation and see the answer as a decimal and, when it has a simple form, as a fraction.
- Combinations and Permutations CalculatorType nCr(n,r) to count unordered choices and nPr(n,r) to count ordered arrangements.
- Exponent and Root CalculatorUse xʸ for powers and √, ∛ and ⁿ√ for roots, in one expression.
- Logarithm CalculatorCalculate log base 10, natural log ln and logarithms to any base.