11 choose 9
Choosing 9 from 11— order doesn't matter.
Combinations (order doesn't matter)
11C9 = 55
Permutations (order matters): 11P9 = 19,958,400
There are 55 ways to choose 9 items from 11when order doesn't matter, using the formula C(n, k) = n! / (k! · (n − k)!).
11 choose k table
| Expression | Combinations |
|---|---|
| 11 choose 0 | 1 |
| 11 choose 1 | 11 |
| 11 choose 2 | 55 |
| 11 choose 3 | 165 |
| 11 choose 4 | 330 |
| 11 choose 5 | 462 |
| 11 choose 6 | 462 |
| 11 choose 7 | 330 |
| 11 choose 8 | 165 |
| 11 choose 9 | 55 |
| 11 choose 10 | 11 |
| 11 choose 11 | 1 |
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Frequently asked questions
What is 11 choose 9?+
11 choose 9 equals 55. It counts the number of ways to choose 9 items from 11 when the order does not matter.
What is the formula for 11 choose 9?+
The combinations formula is C(n, k) = n! / (k! · (n − k)!). For 11 choose 9: 11! / (9! · 2!) = 55.