如何计算Combinations (nCr)

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Combinations (nCr) count the ways to choose r items from n when order does not matter. Fundamental in probability, statistics, and combinatorics.

公式

C(n,r) = n! / (r! × (n−r)!)

C: C(n — C(n

分步指南

1C(n,r) = n! / (r! × (n−r)!)
2Order does NOT matter (unlike permutations)
3C(n,r) = C(n,n−r) — symmetrical property
4C(n,0) = C(n,n) = 1 always

例题解析

输入

Choose 3 from 10

结果

C(10,3) = 120 combinations

常见问题

What is Combinations?

Combinations (nCr) count the ways to choose r items from n when order does not matter. Fundamental in probability, statistics, and combinatorics

How accurate is the Combinations calculator?

The calculator uses the standard published formula for combinations. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Combinations calculator use?

This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.

What formula does the Combinations calculator use?

The core formula is: C(n,r) = n! / (r! × (n−r)!). Each step in the calculation is shown so you can verify the result manually.

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