Combinations Calculator

How to use it

1. Total n = 10, choosing r = 4
2. Apply formula: C(10,4) = 10! ÷ (4! × 6!)
3. Simplify: (10×9×8×7) ÷ (4×3×2×1)
4. Calculate: 5040 ÷ 24 = 210 combinations

Common mistakes

• ⚠️ Using permutations formula instead of combinations
• ⚠️ Not simplifying factorials before calculating
• ⚠️ Confusing combinations with permutations (order matters)

Worked example

Calculate C(10,3)=120.

The combinations {comb} count the number of ways to choose r items from n when order doesn't matter.

Input guide