Big Number Calculator: 1,000+ Digit Precision

Q: How many digits can this calculator handle?

Arithmetic uses high-precision decimal math (about 1,000 significant digits), far beyond the ~15 digits of normal JavaScript floats. Very long result strings may switch to scientific notation on screen (for example after roughly 1,000 characters). Mod and GCD on whole numbers use exact integer arithmetic when the inputs fit.

Q: What is the difference between this and a normal calculator?

Standard IEEE 754 doubles only keep integers exact up to 253 − 1 (about 9 quadrillion). After that, bits get rounded. Here, + − × ÷ and many integer tools keep going until the browser runs out of memory. Division and square roots are different: you choose how many decimal places to show (1–500), and the result rounds to that count.

Q: How does E-notation input work?

Paste or type values like 2.5e+50 or 1.23e-10. They parse into the same high-precision engine as plain decimals. If the expanded result is enormous, the readout may stay in scientific form so the page stays readable; use Copy Raw for the full string when it fits.

Q: What is the precision limit for division and square roots?

Set Precision (1–500) for ÷ and √. Example: 1 ÷ 7 at 20 places gives 0.14285714285714285714 instead of the 16-digit float you get in a spreadsheet. Other operations use the engine default unless the result is rounded for display size.

Q: How does factorial work for very large n?

For n ≤ 170, the tool multiplies 1 × 2 × 3 × … × n and gives every digit of the answer. Above 170, multiplying every factor would produce a number with more digits than this page can compute exactly, so the tool switches to Stirling’s approximation, a standard formula that estimates n!. Good for “how big is 500!?” not for copying all 1,000+ digits of 500!. Negative or non-integer inputs error out.

Q: Copy Raw vs Copy Formatted?

Copy Raw puts the result string in your clipboard as stored (best for code or another tool). Copy Formatted adds comma grouping when digit grouping is on. Toggle grouping on the result if you only want commas in the copy.

Big number calculator: wide precision and honest limits

2^1024 prints all 309 digits here. 1 ÷ 7 to 20 places shows the repeat. Factorials through 170! are exact; 171! and up are estimates. About 1,000 significant digits, not unlimited.

What this calculator does

High-precision arithmetic in the browser: add, subtract, multiply, divide, power (integer exponent), factorial, square root, square (x²), and integer mod, GCD, and LCM. Accepts long integers, decimals, and E-notation. Precision control (1–500 decimal places) applies to division and square roots. Optional comma grouping plus Copy Raw / Copy Formatted.

Outputs:

Result string (grouped or plain), with clipboard copies.
Limits:

About 1,000 significant digits in the engine. Results extremely long on screen may use scientific notation. Factorial exact for n ≤ 170; for n ≥ 171 the answer is a Stirling estimate, not every digit of n!. |exponent| > 1000 on powers may use logarithms. Not a cryptography key generator; it only computes what you type.

The math

Most operations use high-precision decimal math (roughly 1,000 significant digits), avoiding the 2⁵³ integer wall in normal JavaScript numbers. Mod and GCD/LCM use exact integer arithmetic when operands are whole numbers that fit.

Worked: 2^1024:

Integer power with exponentiation by squaring; full 309-digit result, a common “does my tool lose digits?” check.
Worked: 1 ÷ 7:

At 20 decimal places → 0.14285714285714285714. Float math would truncate earlier.
Factorial:

For n ≤ 170, multiply 1×2×…×n for the full integer. For n ≥ 171, Stirling’s approximation estimates the size:
$n! \approx \sqrt{2\pi n}\left(\frac{n}{e}\right)^n$
Example: 500! has well over a thousand digits if written out; the estimate is for magnitude, not a digit-by-digit printout.
Large powers:

Non-integer exponents error. Very large integer exponents may use logarithms for speed, which can introduce rounding in the last digits.
Display:

Divide and √ round to your precision setting (1–500 places). Strings longer than ~1,000 characters may display as scientific notation (e.g. 1.23e+309).
Edge cases:

Division or mod by zero errors. Factorial requires non-negative integers. √ of negatives errors.

Using the calculator

Calculations run automatically after you pause typing (~300 ms). Fix invalid input when the error line appears.

Two-input ops:

+ − × ÷, ^, mod, GCD, LCM need both fields.
One-input ops:

!, √, and x² use the first field only.
Precision field:

Visible for ÷ and √ only; 1–500 decimal places in the result.
E-notation:

2.5e+50 style input; parsing matches plain numbers.
Grouping & copy:

Toggle commas on the result panel; Raw vs Formatted copy as described above.
Privacy:

Math stays in your browser; nothing is sent to a server.

FAQ

How many digits can this calculator handle?

Arithmetic uses high-precision decimal math (about 1,000 significant digits), far beyond the ~15 digits of normal JavaScript floats. Very long result strings may switch to scientific notation on screen (for example after roughly 1,000 characters). Mod and GCD on whole numbers use exact integer arithmetic when the inputs fit.

What is the difference between this and a normal calculator?

Standard IEEE 754 doubles only keep integers exact up to 2⁵³ − 1 (about 9 quadrillion). After that, bits get rounded. Here, + − × ÷ and many integer tools keep going until the browser runs out of memory. Division and square roots are different: you choose how many decimal places to show (1–500), and the result rounds to that count.

How does E-notation input work?

Paste or type values like 2.5e+50 or 1.23e-10. They parse into the same high-precision engine as plain decimals. If the expanded result is enormous, the readout may stay in scientific form so the page stays readable; use Copy Raw for the full string when it fits.

What is the precision limit for division and square roots?

Set Precision (1–500) for ÷ and √. Example: 1 ÷ 7 at 20 places gives 0.14285714285714285714 instead of the 16-digit float you get in a spreadsheet. Other operations use the engine default unless the result is rounded for display size.

How does factorial work for very large n?

For n ≤ 170, the tool multiplies 1 × 2 × 3 × … × n and gives every digit of the answer. Above 170, multiplying every factor would produce a number with more digits than this page can compute exactly, so the tool switches to Stirling’s approximation, a standard formula that estimates n!. Good for “how big is 500!?” not for copying all 1,000+ digits of 500!. Negative or non-integer inputs error out.

Copy Raw vs Copy Formatted?

Copy Raw puts the result string in your clipboard as stored (best for code or another tool). Copy Formatted adds comma grouping when digit grouping is on. Toggle grouping on the result if you only want commas in the copy.

Big Number Calculator

Inputs & Operation

2^1024 in the browser

Four things that change the number you see

Exact until the method changes

Division and roots are on your decimal budget

Integers for mod, GCD, and LCM

Copy and grouping are separate choices