Combinations Formula
Also known as: nCr Formula, Binomial Coefficient
C(n, r) = \binom{n}{r} = \frac{n!}{r!(n-r)!}
C(n,r) = n! / (r!(n-r)!)What It Calculates
Counts the number of ways to choose r items from n, where ORDER DOES NOT MATTER.
variables
| Symbol | Name | Description |
|---|---|---|
| n | Total Items | Total number of items |
| r | Items Chosen | Number of items selected |
Worked Examples
1
C(10,3) = 10! / (3! × 7!)2
= (10×9×8) / (3×2×1) = 720/6 = 120Result: 120
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#combinatorics#probability#counting