Big Number Calculator

Ordinary calculators and spreadsheets store numbers in double-precision floating point, which keeps only about 15 to 17 significant digits. Anything beyond that is silently rounded: ask for 2⁶⁴ and you may see 18446744073709552000 instead of the exact 18446744073709551616. For everyday arithmetic this is harmless, but it is a problem for cryptography, number theory, combinatorics, high-precision science and checking long hand calculations.

This calculator avoids the limit by storing each number as an exact integer of any length together with the position of its decimal point. Addition, subtraction, multiplication, squares, integer powers, factorials, MOD, GCD and LCM are therefore exact to the last digit. Division and square roots usually produce endless decimals, so they are rounded to the number of decimal places you set in the precision box. Inputs can be plain integers, decimals or scientific notation such as 6.02214076e23, and commas are ignored.

Big results can be very big indeed. 1,000! has 2,568 digits, and 2^10,000 has 3,011. The results show the digit count and an approximate value in scientific notation alongside the exact answer.

English speakers today almost always use the short scale, in which each new name is a thousand times the previous one: a billion is 10⁹ and a trillion is 10¹². Some European languages use the long scale, where a billion means 10¹², so check which convention a source uses. The table lists the short-scale names.

MOD returns the remainder after dividing X by Y, with the sign of X, which is how most programming languages define it. GCD and LCM return the greatest common divisor and least common multiple of two whole numbers. X ^ Y requires a whole-number exponent; a negative exponent gives the reciprocal, rounded to the chosen precision. √X uses Newton's method on exact integers and is rounded half away from zero at the last requested place.

Frequently asked questions