12 Choose 11

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Total items (n)
Items chosen (k)

What is 12 choose 11?

Answer

12 choose 11 is
12

Order doesn't matter, no repeats: 12 ways to choose 11 of 12 items.

Choosing 11 of 12 is the same as leaving 1 out: C(12, 11) = C(12, 1).

C(12, 11) = 12! / (11! · 1!)

= C(12, 1)

= 12 / 1

= 12

If order matters (permutations): P(12, 11) = 12 × 11 × 10 × … × 2 = 479,001,600 — each combination in 11! = 39,916,800 orders.

Row 12 of Pascal's triangle
k12 choose k
01
112
266
3220
4495
5792
6924
7792
8495
9220
1066
1112
121

Row sum: 212 = 4,096 — all subsets of 12 items.

See Also

FAQ

What is 12 choose 11?

12 choose 11 is 12

Why is 12 choose 11 the same as 12 choose 1?

Every way to choose 11 of 12 items leaves exactly 1 behind, so choosing 11 and choosing which one to leave out are the same count: 12 choose 11 = 12 choose 1 = 12. In the formula n! / (k! (n − k)!) the two factorials below just swap places.

How many ways are there if order matters?

P(12, 11) = 479,001,600. Each of the 12 combinations can be put in order in 11! = 39,916,800 ways, so permutations = combinations × k!: P(n, k) = n! / (n − k)!.