Big Number Calculator guide
Big Number Calculator: Exact Arithmetic on Huge Numbers
Use our big number calculator to add, subtract, multiply, divide and raise huge whole numbers to powers, with exact results and factorials.
By the AllCalculator editorial teamUpdated 16 October 20261 min read
Ordinary calculators round very big numbers, so you lose digits. Our Big Number Calculator works with whole numbers of any size and gives exact answers.
How to use the calculator (Big Number Calculator)
- Choose an operation: add, subtract, multiply, divide, power, remainder, factorial or greatest common factor.
- Type your whole numbers. You can paste numbers with hundreds of digits.
You'll see the result in short form, how many digits it has and every digit of the exact answer.
Why ordinary calculators lose digits
Most calculators and spreadsheets store about 15 to 17 significant digits. After that, digits are rounded to zeros. This calculator uses exact whole-number arithmetic instead, so every digit is correct.
A worked example
With the calculator's default settings, 123,456,789,012,345,678,901,234,567,890 × 987,654,321,098,765,432,109,876,543,210 is a 60-digit number starting 1.2193263 × 10⁵⁹.
Factorials
n! = n × (n − 1) × … × 1. Factorials grow incredibly fast:
| n | n! |
|---|---|
| 10 | 3,628,800 |
| 20 | 2,432,902,008,176,640,000 |
| 52 | About 8 × 10⁶⁷ (ways to shuffle a deck of cards) |
Frequently asked questions
Can it handle decimals?
No, it works with whole numbers only. For decimals, use our Scientific Calculator.
How does division work?
It gives the whole-number quotient and the remainder, like long division.
Is there a limit?
Results are limited to 100,000 digits, and factorials to 5,000!, so the page stays fast.
Sources and further reading
Links open official and independent websites in a new tab.
This guide is general information to help you understand your options. It isn't financial, tax, legal or building advice and doesn't take your personal circumstances into account. Figures were checked when the guide was last updated and can change, so confirm anything important with GOV.UK, HMRC, a regulated adviser or a qualified tradesperson.