4 Choose 0

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Items chosen (k)

What is 4 choose 0?

Answer

4 choose 0 is
1

Order doesn't matter, no repeats: 1 way to choose 0 of 4 items.

There is exactly one way: take none.

C(4, 0) = 4! / (0! · 4!)

= 1

0! = 1 (an empty product), so 4! cancels out completely.

Row 4 of Pascal's triangle
k4 choose k
01
14
26
34
41

Row sum: 24 = 16 — all subsets of 4 items.

See Also

FAQ

What is 4 choose 0?

4 choose 0 is 1

Why is 4 choose 0 the same as 4 choose 4?

Every way to choose 0 of 4 items leaves exactly 4 behind, so choosing 0 and choosing which 4 to leave out are the same count: 4 choose 0 = 4 choose 4 = 1. In the formula n! / (k! (n − k)!) the two factorials below just swap places.

How many ways are there if order matters?

The same 1: with 0 chosen items there is only one order, so P(4, 0) = 4 choose 0 = 1. Order starts to matter from 2 items on: n × (n − 1) arrangements.