Big Numbers Calculator — Up to 1,000 Digits
Add, subtract, multiply and compare signed integers up to 1,000 digits exactly. Divide with rounding to 0–20 decimal places; decimal inputs are not supported.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Add, subtract, compare and multiply whole numbers exactly, without floating-point limits. Division is rounded to the selected number of decimal places. Enter signed integers only; each input can contain up to 1,000 digits.
Worked example
calculated with the default values below
First number 123456789012345678901234567890 · Second number 987654321098765432109876543210 · Operation Add · Number of decimal places in the result 0 Result 1111111110111111111011111111100 · Digits in the result 31 digits · Magnitude of A (absolute value; approximate) 1.23 × 10^29 · Comparison B is larger · Note Integer operations are exact. Division is rounded to the selected decimal places; each input accepts up to 1,000 digits and an optional minus sign.
Method and assumptions
Addition, subtraction and multiplication use arbitrary-size integer arithmetic. Division uses integer quotient and remainder arithmetic, rounds halfway cases away from zero, and omits trailing fractional zeros. For example, −1 ÷ 8 at two decimal places is −0.13; 1 ÷ 2 at zero places is 1. The digit count includes digits in the displayed numeric result, excluding its sign and decimal point, and is unavailable for a comparison-only result. The magnitude row describes the absolute value of input A, not the result: short-scale names are used through septillion, then scientific notation. Its leading digits are truncated to two decimal places rather than rounded.
General background references
Disclaimer
These calculators give general estimates. Sizing, pricing, availability and standards vary by brand, retailer and country, so treat the output as a starting point and confirm it against the seller's or authority's own figures.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
r = a + b | a − b | a × b; r ≈ a ÷ b (n d.p.)
- a
- First large integer
- b
- Second large integer
- n
- Decimal places for division
- r
- Result
Signed whole-number inputs only, up to 1000 digits each. BigInt addition, subtraction and multiplication are exact. Division uses integer quotient/remainder arithmetic and rounds halfway values away from zero to 0–20 decimal places; it does not convert the operands to floating-point numbers. Decimal inputs are rejected rather than truncated.
Frequently asked questions
Which operations are exact, and how is division rounded?
Use whole-number digits with an optional leading minus sign. Spaces around the input are trimmed. Decimal points, comma separators, exponent notation and plus signs are rejected. Each input accepts up to 1000 digits, including leading zeros. Integer addition, subtraction and multiplication are exact. Division is rounded to 0–20 selected decimal places using integer arithmetic, with halfway cases rounded away from zero. Trailing decimal zeros are removed. Division by zero is rejected. No. It describes the absolute value of the first input, A, using short-scale names or scientific notation. The separate result row contains the selected operation; the comparison row always compares the original A and B.