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Big Number Calculator

Exact arithmetic on numbers of any size, using BigInt.

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Result

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Digits in the result

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Details

Digits in a—
Digits in b—
Remainder—
Sign—

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Whether an ordinary calculator could hold this

Ordinary calculators use 64-bit floating point, which is exact only up to 9,007,199,254,740,991. Past that they silently lose the low digits. This tool uses arbitrary-precision integer arithmetic, so every digit shown is correct.

Quick Tool Overview

The Big Number Calculator does exact arithmetic on integers far beyond the point where ordinary calculators silently lose precision. Addition, multiplication, powers, factorials and modular exponentiation all return every digit correctly.

What it does
Exact arithmetic on arbitrarily large integers
You give it
Integers of any length and an operation
You get back
An exact result with a digit count
Best for
Cryptography, combinatorics and number theory
Calculators Free, unlimited use No sign-up Runs in your browser

About the Big Number Calculator

Do arithmetic on integers far larger than a normal calculator can hold, with every digit exact. Addition, subtraction, multiplication, integer division, remainder, powers, factorials and modular exponentiation are all supported.

Ordinary calculators and most programming defaults store numbers as 64-bit floating point, which is exact only up to about 9,007,199,254,740,991. Past that, results silently lose their low digits — the answer looks plausible and is wrong. This tool uses arbitrary-precision integer arithmetic instead, so a 200-digit product is correct in every digit. That matters for cryptography, combinatorics and number theory, where the interesting questions usually live well above the floating-point limit.

Key features of the Big Number Calculator

Arbitrary precision

Uses BigInt rather than 64-bit floating point, so results stay exact past 9,007,199,254,740,991 where normal calculators fail.

Factorials and powers

Large factorials and exponentiations that overflow ordinary tools are computed in full.

Modular exponentiation

Computes a^b mod n without forming the enormous intermediate — the core operation behind RSA.

Quotient and remainder

Integer division returns both parts rather than a lossy decimal approximation.

Copy the full result

Results of thousands of digits can be copied out whole, with the digit count shown.

How to use the Big Number Calculator

  1. 1

    Enter your numbers

    Type or paste integers of any length. Commas and spaces are ignored.

  2. 2

    Choose an operation

    Add, subtract, multiply, divide, remainder, power, factorial or modular power.

  3. 3

    Read the exact result

    Every digit is correct — nothing is rounded or truncated.

  4. 4

    Copy it out

    The result can be copied in full, with a digit count shown alongside.

Frequently asked questions

They use 64-bit floating point, which is exact only up to 9,007,199,254,740,991. Beyond that the low digits are silently lost, so results look reasonable but are incorrect.

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