Big Number Calculator
Perform exact arithmetic on integers of any size — no rounding, no overflow. Powered by JavaScript BigInt for arbitrary-precision results.
Result (a × b)
1,219,326,311,370,217,952,237,463,801,111,263,526,900
- Result (no separators)
- 1219326311370217952237463801111263526900
- Digit count
- 40
How to use this calculator
Type two whole numbers — as large as you like — into fields A and B. Pick an operation (+, −, ×, ÷, mod, power). The calculator returns the exact result, no matter how many digits it has, along with the total digit count. Commas and underscores in the input are ignored, so you can paste numbers like 1,000,000 or 1_000_000 freely. Division returns the integer quotient (the remainder is shown via the modulo operation instead).
How the calculation works
Most calculators store numbers as 64-bit floating-point values, which loses precision above roughly 9 × 10¹⁵ — try multiplying 9007199254740993 × 2 in a normal calculator and you will get an even number back. This tool uses JavaScript BigInt, an arbitrary-precision integer type built into the language since ECMAScript 2020. There is no upper size limit on the inputs or the result (the only practical cap is the exponent for the power operation, which is held at 10,000 to keep the browser responsive). Every arithmetic operation is exact.
Worked example
A famous big-number problem is 2¹⁰⁰. A standard calculator gives 1.2676506002282294e+30 — only the first 16 digits are correct. This tool returns the exact 31-digit answer: 1,267,650,600,228,229,401,496,703,205,376. Another example: multiplying two 20-digit primes such as 12,345,678,901,234,567,891 × 98,765,432,109,876,543,211 produces a 40-digit product (1,219,326,311,370,217,952,348,574,912,122,374,638,001) with every digit accurate — exactly the kind of computation that overflows ordinary calculators.
Frequently asked questions
What is a big number calculator?
A big number calculator (sometimes called an arbitrary-precision calculator) computes with integers of any size, with no loss of precision. Standard calculators use 64-bit floating-point arithmetic, which can only represent integers exactly up to about 9 quadrillion (2⁵³ - 1). Above that, results are rounded. A big number calculator stores each number as a sequence of digits and applies long-arithmetic algorithms internally, so a 100-digit product is just as exact as a 5-digit product.
How large can the numbers be?
There is no fixed upper limit on the size of inputs A and B or the result. The numbers are stored as JavaScript BigInts, which are bounded only by available memory. In practice you can comfortably work with numbers tens of thousands of digits long. The one tunable cap is the power operation: the exponent is capped at 10,000 to prevent the browser from hanging on a runaway computation (10,000^10,000 has 40,001 digits — that finishes in milliseconds).
What does the modulo operation do?
Modulo (written a mod b) returns the remainder after dividing a by b. For example, 17 mod 5 = 2 because 17 ÷ 5 is 3 remainder 2. Modulo is essential in cryptography (RSA, Diffie–Hellman), hashing, and any time you need to wrap a value into a fixed range (such as converting seconds into hours and minutes). The result takes the sign of the dividend: -17 mod 5 = -2 in this calculator, matching the JavaScript BigInt specification.
Why does division give an integer result?
BigInt arithmetic is exact integer arithmetic — there is no fractional part. Division here returns the integer quotient (the whole-number part of a ÷ b, truncated toward zero); the remainder is available through the modulo operation. If you need a decimal answer, divide the inputs by a power of 10 first, or use the standard calculator for the fractional case. For 17 ÷ 5 the integer result is 3, with 17 mod 5 = 2 capturing the leftover.
Does this work with negative numbers?
Yes. Prefix either input with a minus sign (e.g. -12345). All six operations handle negatives correctly. Subtraction can produce a negative result; multiplication and division follow the standard sign rules (negative × negative = positive). The power operation requires a non-negative exponent, since a negative power of an integer is generally not an integer.
What is BigInt in JavaScript?
BigInt is a primitive numeric type added to JavaScript in ECMAScript 2020. Unlike the standard Number type (which is a 64-bit float), BigInt represents integers of arbitrary length using a dedicated representation in the engine. BigInt literals are written with a trailing n in code (123n), and the same arithmetic operators work — but mixing BigInt with Number throws a TypeError, since silently converting between exact and inexact representations would defeat the point. This calculator uses BigInt under the hood.