Big Number Calculator

Add, subtract, multiply, divide, raise to powers and take factorials of very large whole numbers, with exact results and no rounding at all.

Formulas last reviewed: September 2026

Enter your details

First whole number

Any size — commas and spaces are ignored.

Operation

Second whole number

Result

1.21932 × 10^59

60 digits

Exact result

Digits: 60
Approximately: 1.21932 × 10^59

Full number

121,932,631,137,021,795,226,185,032,733,622,923,332,237,463,801,111,263,526,900

Disclaimer: Results are calculated with standard formulas and are meant for learning and quick checks. Please double-check important work, especially anything used for exams, engineering, finance or safety.

Exact answers for huge numbers

Ordinary calculators and spreadsheets switch to approximate floating-point numbers after about 15 digits. A big number calculator keeps every digit, so you can add, subtract, multiply, divide, raise to powers, take remainders, find the GCF and compute factorials of enormous integers exactly.

This matters in number theory, cryptography, puzzles and checking large factorials or powers where every digit counts.

How it is calculated

Whole-number arithmetic with no rounding

n! = n × (n − 1) × … × 2 × 1

Division gives a quotient and a remainder

Worked example

25 factorial

25!: 15511210043330985984000000
Number of digits: 26

How big is big?

Numbers grow astonishingly fast. Factorials and powers reach hundreds of digits after only a few steps, which is exactly where ordinary calculators stop being exact.

Value	Digits
2^64	20
20!	19
100!	158
2^1000	302

Results with more than 24 digits are summarised on top, and the full exact number is shown below for you to copy.

Frequently asked questions

Is there a limit on the size?

Inputs can be very long, but results are limited to a size your browser can show comfortably, and factorials above 3,000 are refused.

Does it work with decimals?

No, this tool works with whole numbers only so that every result is exact. Use the scientific notation calculator for decimals.

Why do normal calculators lose digits?

They store numbers in 64-bit floating point, which holds only about 15 to 17 significant digits.

What does mod mean?

A mod B is the remainder after dividing A by B. It is widely used in cryptography and programming.