13 Choose 4

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Total items (n)
Items chosen (k)

What is 13 choose 4?

Answer

13 choose 4 is
715

Order doesn't matter, no repeats: 715 ways to choose 4 of 13 items.

C(13, 4) = 13! / (4! · 9!)

= (13 × 12 × 11 × 10) / (4 × 3 × 2 × 1)
= 17,160 / 24

= 715

If order matters (permutations): P(13, 4) = 13 × 12 × 11 × 10 = 17,160 — each combination in 4! = 24 orders.

Row 13 of Pascal's triangle
k13 choose k
01
113
278
3286
4715
51,287
61,716
71,716
81,287
9715
10286
1178
1213
131

Row sum: 213 = 8,192 — all subsets of 13 items.

See Also

FAQ

What is 13 choose 4?

13 choose 4 is 715

Why is 13 choose 4 the same as 13 choose 9?

Every way to choose 4 of 13 items leaves exactly 9 behind, so choosing 4 and choosing which 9 to leave out are the same count: 13 choose 4 = 13 choose 9 = 715. In the formula n! / (k! (n − k)!) the two factorials below just swap places.

How many ways are there if order matters?

P(13, 4) = 17,160. Each of the 715 combinations can be put in order in 4! = 24 ways, so permutations = combinations × k!: P(n, k) = n! / (n − k)!.