Big Number Calculator
Do arithmetic on very large or very precise numbers — integers, decimals, or E-notation like 3.5e19 — without the rounding errors of a standard calculator.
What is a big number calculator?
Most everyday calculators — and JavaScript's own Number type — use 64-bit floating-point, which keeps only about 15 to 17 significant digits. Anything longer is rounded off, so a multiplication like 123,456,789,012,345 × 987 quietly loses accuracy in the trailing digits.
A big number calculator uses arbitrary-precision arithmetic instead. It stores each number as a full sequence of digits and does the operation the way you would on paper, so the answer is exact for integers and rounded only where a truly irrational result forces it (division, roots, non-integer powers).
Big numbers show up all over the place: cryptography (RSA keys are hundreds of digits long), cosmology and astronomy (distances in metres, atoms in the observable universe), chemistry (Avogadro's constant is 6.022 × 10²³), combinatorics (52! is the number of possible shuffles of a deck), and computer science (the number of addresses in a 128-bit space).
Big number calculator, piece by piece
Each card explains one thing the tool does that a normal calculator can't — how it stores numbers digit-by-digit, how the arithmetic operators behave once precision is unlimited, and how the number-theory helpers (n!, GCD, LCM, MOD) build on that.
Digit-by-digit storage — why 50! comes out complete
A standard hardware float keeps only about 15–17 significant digits, so anything past 2⁵³ silently rounds. This calculator stores each number as its full string of digits and does the arithmetic the way you would on paper. That is why 50! prints all 65 digits instead of collapsing into scientific notation, and why 2¹⁰⁰ prints exactly.
How + − × ÷ ^ √ behave once precision is unlimited
Integer add, subtract and multiply are always exact — no rounding happens because the result of two integers is another integer. Divide, root, and non-integer power are the only operations that force a rounded answer, and they round to the precision setting you choose (default 64 digits). E-notation entries like 3.5e19 stay literal: mantissas multiply, exponents add.
n!, GCD, LCM, MOD — the integer helpers built on top
Factorial chains the multiplication from 1 up to n (with 0! defined as 1). GCD uses the Euclidean algorithm — replace the pair (a, b) with (b, a mod b) until b is zero. LCM is derived from GCD by |a·b|/gcd(a,b). MOD is the remainder after integer division. Because the base representation is arbitrary-precision, all four run without overflow no matter how many digits you feed them.
Powers of 10 and their names
| Powers of 10 | Name |
|---|---|
| 10⁹ | Billion |
| 10¹² | Trillion |
| 10¹⁵ | Quadrillion |
| 10¹⁸ | Quintillion |
| 10²¹ | Sextillion |
| 10²⁴ | Septillion |
| 10²⁷ | Octillion |
| 10³⁰ | Nonillion |
| 10³³ | Decillion |
| 10³⁶ | Undecillion |
| 10¹⁰⁰ | Googol |
| 10³⁰³ | Centillion |
Common mistakes
- Assuming a regular calculator is precise enough. Anything beyond ~15 significant digits silently rounds on a standard float — the trailing digits you see may be noise.
- Confusing the E in E-notation with the X^Y button. 3.5e19 means "3.5 × 10¹⁹" — a single number. To raise 3.5 to the 19th power, enter 3.5 in X, 19 in Y, and press X^Y.
- Using factorial, GCD, LCM or MOD on decimals. These operations require whole numbers. The calculator flags the input rather than returning a misleading value.
- Requesting √ of a negative number. There is no real square root; use a complex-number tool if you need one.
Features of this calculator
- Arbitrary-precision arithmetic — no silent overflow above 15 significant digits
- Accepts integers, decimals, and E-notation (e.g. 3.5e19, 23E18)
- Eleven operations: +, −, ×, ÷, powers, square, square root, factorial, MOD, GCD, LCM
- Adjustable precision (1 – 1000 digits after the decimal point)
- Copy button on results so long numbers move cleanly into your notes
Frequently asked questions
+How many digits can this calculator handle?
Internally the calculator keeps hundreds of significant digits. You control how many appear after the decimal point via the precision field (1 – 1000).
+What is E-notation?
Shorthand for scientific notation. bEn means b × 10ⁿ. For example, 3.5e19 is 3.5 × 10¹⁹.
+Why does my division return a ‘…’ or a rounded value?
Some divisions and roots have infinitely many digits. The result is rounded to the precision you set — raise the precision to see more digits.
+Is a factorial input capped?
Yes, factorial is capped at 50,000 to keep the browser responsive. Even 10,000! has more than 35,000 digits.
+Can I use the result as the next input?
Yes — copy the result, paste it into X or Y, and continue calculating.