Evaluate the combination:
20C10
A unique order or arrangement
nCr = | n! |
r!(n - r)! |
where n is the number of items
r is the unique arrangements.
20C10 2 | 20! |
10!(20 - 10)! |
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 - 10)!
(20 - 10)! = 10!
10! = 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1
10! = 3,628,800
r! = 10!
10! = 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1
10! = 3,628,800
20C10 = | 2,432,902,008,176,640,000 |
3,628,800 x 3,628,800 |
20C10 = | 2,432,902,008,176,640,000 |
13,168,189,440,000 |