Evaluate the combination:
20C18
A unique order or arrangement
nCr = | n! |
r!(n - r)! |
where n is the number of items
r is the unique arrangements.
20C18 2 | 20! |
18!(20 - 18)! |
n! = n * (n - 1) * (n - 2) * .... * 2 * 1
n! = 20!
20! = 20 x 19 x 18 x 17 x 16 x 15 x 14 x 13 x 12 x 11 x 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1
20! = 2,432,902,008,176,640,000
(n - r)! = (20 - 18)!
(20 - 18)! = 2!
2! = 2 x 1
2! = 2
r! = 18!
18! = 18 x 17 x 16 x 15 x 14 x 13 x 12 x 11 x 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1
18! = 6,402,373,705,728,000
20C18 = | 2,432,902,008,176,640,000 |
6,402,373,705,728,000 x 2 |
20C18 = | 2,432,902,008,176,640,000 |
12,804,747,411,456,000 |
20C18 = 190
20C18 = 190
Free Permutations and Combinations Calculator - Calculates the following:
Number of permutation(s) of n items arranged in r ways = nPr
Number of combination(s) of n items arranged in r unique ways = nCr including subsets of sets
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