9 choose 2
Choosing 2 from 9— order doesn't matter.
Combinations (order doesn't matter)
9C2 = 36
Permutations (order matters): 9P2 = 72
There are 36 ways to choose 2 items from 9when order doesn't matter, using the formula C(n, k) = n! / (k! · (n − k)!).
9 choose k table
| Expression | Combinations |
|---|---|
| 9 choose 0 | 1 |
| 9 choose 1 | 9 |
| 9 choose 2 | 36 |
| 9 choose 3 | 84 |
| 9 choose 4 | 126 |
| 9 choose 5 | 126 |
| 9 choose 6 | 84 |
| 9 choose 7 | 36 |
| 9 choose 8 | 9 |
| 9 choose 9 | 1 |
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Frequently asked questions
What is 9 choose 2?+
9 choose 2 equals 36. It counts the number of ways to choose 2 items from 9 when the order does not matter.
What is the formula for 9 choose 2?+
The combinations formula is C(n, k) = n! / (k! · (n − k)!). For 9 choose 2: 9! / (2! · 7!) = 36.