20 Choose 10
Combination Calculator
What is 20 choose 10?
Answer
20 choose 10 is
184,756
Order doesn't matter, no repeats: 184,756 ways to choose 10 of 20 items.
C(20, 10) = 20! / (10! · 10!)
= (20 × 19 × 18 × … × 11) / (10 × 9 × 8 × … × 1)
10 factors on top and bottom
= 670,442,572,800 / 3,628,800
= 184,756
If order matters (permutations): P(20, 10) = 20 × 19 × 18 × … × 11 = 670,442,572,800 — each combination in 10! = 3,628,800 orders.
| k | 20 choose k |
|---|---|
| 0 | 1 |
| 1 | 20 |
| 2 | 190 |
| 3 | 1,140 |
| 4 | 4,845 |
| 5 | 15,504 |
| 6 | 38,760 |
| 7 | 77,520 |
| 8 | 125,970 |
| 9 | 167,960 |
| 10 | 184,756 |
| 11 | 167,960 |
| 12 | 125,970 |
| 13 | 77,520 |
| 14 | 38,760 |
| 15 | 15,504 |
| 16 | 4,845 |
| 17 | 1,140 |
| 18 | 190 |
| 19 | 20 |
| 20 | 1 |
Row sum: 220 = 1,048,576 — all subsets of 20 items.
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See Also
- Random Number Generator - Pick a random whole number between two bounds
- Percent to Probability Converter - Convert Percents to "1 in X" Probability Chance
- Factors of a Number - List all Factors and Factor Pairs of a Number
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