About the Permutation & Combination Calculator
Computes nPr and nCr, with and without repetition, using exact arithmetic.
What it is
Enter n and r, choose a mode, and get an exact result computed with BigInt arithmetic — so factorials stay precise even for large n — along with the fully substituted formula.
Features
Four modes
nPr, nCr, and their with-repetition variants.
Exact large-number arithmetic
BigInt keeps factorials precise; huge results switch to scientific notation.
Step-by-step working
The factorial formula shown fully substituted.
Input validation
r > n without repetition is flagged, not silently wrong.