Permutation Calculator
Calculate nPr, the number of ordered arrangements of r items from n.
What is Permutation?
A permutation is an ordered selection: choosing r items from n and caring which came first. The count is nPr = n! ÷ (n − r)!, which is larger than the matching combination by exactly the r! orderings of each set.
How it works
The engine multiplies the r terms of the falling factorial using BigInt, so the result is exact even when it runs to dozens of digits — a floating-point calculation quietly loses the last digits of nPr past n = 20. Inputs that would divide by zero or ask for more items than exist are reported rather than returned as NaN.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.