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- Adds, subtracts, multiplies and divides whole numbers of any size, up to 5,000 digits each.
- Gives exact answers, with no rounding and no 1.23E+45 shortcuts.
- Raises numbers to powers up to 10,000, and finds A mod B and the GCD.
- Shows how many digits the answer has and its scientific notation.
How to use the big number calculator
Enter the first number (A)
Type or paste a whole number. A minus sign is allowed; commas and decimals are not.
Pick the operation
Add, subtract, multiply, divide (quotient and remainder), power, mod or GCD.
Enter the second number (B)
For a power, B is the exponent.
Copy the exact result
The full answer is shown with its digit count and scientific notation.
Why normal calculators fail with big numbers
Most calculators and spreadsheets store numbers with about 15 to 17 significant digits. Anything longer is rounded, so 2^100 shows as 1.26765E+30 and the last digits are lost. This calculator uses exact integer arithmetic (BigInt), so every digit of the answer is correct.
What each operation returns
A ÷ B = quotient remainder r, where A = B × quotient + r
A mod B = the remainder after dividing A by B
GCD(A, B) = the largest number that divides both A and B
Division works on whole numbers, so you get a whole-number quotient and a remainder rather than a decimal.
Example 1: multiplying two 30-digit numbers
A = 123456789012345678901234567890, B = 987654321098765432109876543210
- A + B 1,111,111,110,111,111,111,011,111,111,100
- A × B 121932631137021795226185032733622923332237463801111263526900
- Digits in A × B 60
Example 2: powers of 2
Exact values a phone calculator cannot show.
- 2^100 1,267,650,600,228,229,401,496,703,205,376
- 2^1000 ≈ 1.071508 × 10^301 (302 digits)
Example 3: division and GCD
Whole-number answers.
- 100 ÷ 7 14 remainder 2
- GCD(462, 1071) 21
Where a big number calculator helps
Math and number theory
Check factorials, powers and large products exactly.
Programming
Verify results that overflow 64-bit integers.
Cryptography learning
Practise modular arithmetic with large numbers.
Puzzles and curiosity
See every digit of numbers like 2^1000.
For very large or very small decimals, use the scientific notation calculator. For powers with decimals, try the exponent calculator, and to break a number into primes use the prime factorization calculator.
Big number calculator FAQ
How big can the numbers be?
Each number can have up to 5,000 digits, and powers can go up to an exponent of 10,000.
Are the results exact?
Yes. The calculator uses exact integer arithmetic, so no digits are rounded or lost.
Can I use decimals?
No, it works with whole numbers only. For decimals, use the scientific notation or decimal calculator.
Why does Excel show large numbers wrong?
Excel keeps only 15 significant digits, so the rest are replaced with zeros.
What does mod mean?
A mod B is the remainder after dividing A by B. For example, 100 mod 7 = 2.
What is the value of 2 to the power of 100?
2^100 = 1,267,650,600,228,229,401,496,703,205,376, a 31-digit number.