Add, subtract, multiply, or divide integers of virtually unlimited size with exact, arbitrary-precision math.

How to Use the Big Number Calculator

Type or paste two whole numbers of any length into the two fields, pick an operation, and the result updates immediately — dividing shows both the quotient and the remainder, since integer division on numbers this size can't just be rounded away.

Regular numbers in JavaScript — and in most calculators, spreadsheets, and apps — lose exact precision above 9,007,199,254,740,991 (Number.MAX_SAFE_INTEGER). Past that point, adding 1 to a number can silently return the same number back, or the wrong neighboring one, with no error or warning that anything went wrong. That's not a rare edge case for a tool specifically built to handle 30-digit numbers by default — it's the entire reason this calculator exists.

BigInt(text) → exact integer arithmetic, no size ceiling
quotient = a / b   (truncated toward zero)
remainder = a % b

This Big Number Calculator parses both inputs with JavaScript's native BigInt type, which represents integers exactly no matter how many digits they run to — there's no floating-point approximation happening, so there's nothing to round. Division is the operation worth a second look: BigInt division truncates any fractional part instead of returning a decimal, so 100 divided by 7 comes back as a quotient of 14 with a separate remainder of 2, not 14.2857.

Numbers past the safe-integer ceiling aren't just a curiosity, either. Cryptographic key generation routinely works with numbers hundreds of digits long. Factorials get enormous fast — 25! alone is already a 26-digit number. Arbitrary-precision arithmetic is simply what's required any time an exact answer matters more than an approximation that looks right until it quietly isn't.