Quick answer
The calculator does exact integer arithmetic on numbers of any practical size. 123456789012345678901234567890 × 987654321098765432109876543210 = 121,932,631,137,021,795,226,185,032,733,622,923,332,237,463,801,111,263,526,900 (60 digits).
Enter two integers and choose an operation. The result is exact, with a digit count. It works as a big number calculator for exact integer arithmetic.
Related tools: Number Sequence Calculator: Identify an arithmetic or geometric sequence and find the next terms. Prime Number Calculator: Check whether a number is prime and find the next prime. Complex Number Calculator: Add, subtract, multiply and divide complex numbers.
How to use the Big Number Calculator
- Type first integer.
- Type second integer.
- Choose operation: Add, Subtract, Multiply, Integer divide, Remainder and Power.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| First integer | Text | — |
| Second integer | Text | — |
| Operation | Choose one: Add; Subtract; Multiply; Integer divide; Remainder; Power | Starts at Add |
Formula and method
Formula
exact arbitrary-precision integer arithmetic
IEEE-754 double precision; shown to the decimals indicated.
Division returns the quotient rounded toward negative infinity for positive numbers; powers are limited to results under 20,000 digits.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: First integer = 123456789012345678901234567890; Second integer = 987654321098765432109876543210; Operation = Multiply.
| Result | Value |
|---|---|
| Result | 121,932,631,137,021,795,226,185,032,733,622,923,332,237,463,801,111,263,526,900 |
| Digits | 60 |
Example 2
Inputs: First integer = 2; Second integer = 100; Operation = Power.
| Result | Value |
|---|---|
| Result | 1,267,650,600,228,229,401,496,703,205,376 |
| Digits | 31 |
Example 3
Inputs: First integer = 1000000000000000000000; Second integer = 7; Operation = Remainder.
| Result | Value |
|---|---|
| Result | 6 |
| Digits | 1 |
The first line is the headline result (result). Below it the big Number Calculator lists digits, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Why not a normal calculator
Standard calculators and JavaScript numbers lose precision above 2⁵³ (about 9 × 10¹⁵), rounding to the nearest representable value. This tool uses arbitrary-precision integers, so every digit is correct.
Integers only
Division returns an integer quotient and remainder, not a decimal. Only whole numbers are supported; use a decimal calculator for fractions.
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- First integer: entering "1.5" shows "Enter a whole number." beside that field and no result.
- Second integer: entering "0" shows "Cannot divide by zero." beside that field and no result.
Choosing between the Big Number Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Number Sequence Calculator](/math/number-sequence-calculator/) | sequence | Pattern |
| [Prime Number Calculator](/math/prime-number-calculator/) | number | Result |
| [Complex Number Calculator](/math/complex-number-calculator/) | real part of z₁, imaginary part of z₁ and operation | Result |
| [Random Number Generator](/math/random-number-generator/) | minimum, maximum and how many | Random numbers |
| [Fraction to Mixed Number Calculator](/math/fraction-to-mixed-number-calculator/) | numerator and denominator | Mixed number |
Assumptions and limitations
- Integers only
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for first integer and second integer to confirm this.
Frequently asked questions
How large can numbers be?
Limited by memory and input length.
Does it show scientific notation?
No, it shows all digits.
What about exponents?
Use repeated multiplication or the factorial calculator.
What does the Big Number Calculator calculate?
Exact arithmetic on integers of any size. It returns Result and Digits.
What formula does the Big Number Calculator use?
exact arbitrary-precision integer arithmetic. Division returns the quotient rounded toward negative infinity for positive numbers; powers are limited to results under 20,000 digits.
What do I need to enter in the big Number Calculator?
You enter First integer, Second integer and Operation.
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Integers only.
What does the “Operation” option change?
It sets how the big Number is worked out. The choices are Add, Subtract, Multiply, Integer divide, Remainder and Power.
What is an example of a big Number result?
With first integer 123456789012345678901234567890, second integer 987654321098765432109876543210 and operation Multiply, the result is 121,932,631,137,021,795,226,185,032,733,622,923,332,237,463,801,111,263,526,900.
Where does the method come from?
The method follows: Arbitrary-precision integer arithmetic.
Related calculators
- Number Sequence Calculator — Identify an arithmetic or geometric sequence and find the next terms.
- Prime Number Calculator — Check whether a number is prime and find the next prime.
- Complex Number Calculator — Add, subtract, multiply and divide complex numbers.
- Random Number Generator — Random integers in a range, optionally repeatable with a seed.
- Fraction to Mixed Number Calculator — Convert an improper fraction to a mixed number.
- Mixed Number to Fraction Calculator — Convert a mixed number to an improper fraction.
- Cartesian to Polar Converter — Radius and angle from x and y.
- Pie Chart Calculator — Shares and slice angles for a set of values.
- Rational or Irrational Calculator — Whether the k-th root of a whole number is rational.
Sources
- Arbitrary-precision integer arithmetic
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.