Big Number Calculator
The Big Number Calculator works with numbers far beyond what a normal calculator can handle, computing on values with hundreds of digits without rounding them off or collapsing them into scientific notation. It is built for anyone who hits the limits of a standard calculator, from students checking a 1000! factorial to programmers and curious tinkerers who need exact big-integer math.
Type or paste two numbers, pick an operation, and read the exact result along with its digit count. You can add, subtract, multiply, divide, take powers and roots, find a factorial, or compute the GCD and LCM of huge integers, then show the answer in decimal, scientific, or engineering notation or even spelled out in words.
How to Use the Big Number Calculator
Enter your numbers
Type or use Paste to drop a number into the Number X and Number Y fields. There is no digit limit, scientific notation like 1.5e20 is accepted, and a live counter shows how many digits each input holds.
Pick an operation
Choose from add, subtract, multiply, divide, modulo, power (XY), square, square root, factorial, GCD, or LCM. Single-number operations such as square, square root, and factorial automatically hide the second input.
Adjust the options
Set the Decimal places used for division and roots, choose an output format (decimal, scientific, or engineering), toggle Digit grouping for readable commas, and turn on Show as words to spell the result out.
Calculate and reuse
Click Calculate or press Enter to see the result, its formula, and its digit count. Use Swap to exchange X and Y, Use as X to chain a result into the next calculation, or reopen any item from the saved history.
Features
Arbitrary Precision Arithmetic
Calculate with numbers of any length, well past the 15-to-17 digit limit of standard calculators, with results carried to high precision.
Comprehensive Operations
Add, subtract, multiply, divide, modulo, raise to a power, square, take a square root, and find factorials, GCD, and LCM.
Exact Integer Results
Integer operations like addition, multiplication, modulo, factorial, GCD, and LCM return exact answers with no rounding error.
Multiple Display Formats
Show results in decimal with optional digit grouping, in compact scientific notation, or in engineering notation with exponents in multiples of three.
Number to Words
Spell a result out in words in your current page language, with support for negatives and decimals up to each language's digit limit.
Calculation History
Recent calculations are saved in your browser and reloaded with one click, surviving page refreshes until you clear them.
Number Names Reference
A built-in table maps big number names from thousand up to googol to their zero count and power of ten.
Private and Offline
All processing happens in your browser, nothing is sent to a server, and the tool keeps working without an internet connection.
Frequently Asked Questions
What is a big number (arbitrary precision) calculator?
It is a calculator that computes with numbers far larger than a normal calculator allows. Standard tools lose precision after about 15 to 17 significant digits and fall back to scientific notation or errors. Arbitrary precision arithmetic keeps every digit, so you get exact answers for very large integers.
How many digits can the calculator handle?
There is no fixed digit limit on the inputs, and results can run to hundreds of digits. Two operations are capped for performance: the power exponent and the factorial input each have a maximum of 10000. Very large calculations may simply take a moment longer to compute.
How do I calculate the factorial of a large number, such as 1000!?
Enter the number in the X field, select the n! operation (it does not need a Y value), and click Calculate. Factorials are defined only for non-negative integers, and the input is capped at 10000, so values like 1000! are computed exactly and shown with their full digit count.
Why does a normal calculator show scientific notation or an error for big numbers?
Standard calculators and most programming languages store numbers in fixed-size formats. JavaScript, for example, is only exact up to about 16 digits, and 64-bit integers top out near 18 quintillion. Beyond that, results are rounded and displayed in scientific notation. This tool uses arbitrary precision instead, so big numbers stay intact.
Can it multiply and divide very large integers exactly?
Multiplication of integers is always exact. Division can produce infinitely repeating decimals (such as 1 divided by 3), so it is rounded to the number of decimal places you choose. For an exact whole-number remainder, use the MOD operation alongside division.
Can I enter numbers in scientific notation?
Yes. Enter values like 1.5e20 (which equals 150,000,000,000,000,000,000) and the calculator parses them correctly. Thousand separators and spaces in your input are ignored, so pasted numbers still work.
What does "number too large for words" mean?
The Show as words option converts results to text in your current page language, and each language can only spell out numbers up to a certain size. English handles up to 30 digits and Vietnamese up to 18, for example, so anything past a language's limit cannot be written in words even though it still calculates exactly.
Is it free and does it work online without downloading anything?
Yes. It runs in any modern browser with nothing to install or sign up for. All calculations happen locally on your device, your history is stored only in your own browser, and the tool keeps working offline once the page has loaded.
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