Question 388972
100C4

Find the number of possible unordered combinations when r items are selected from n available items.
100C4=nCr=(n!)/(r!(n-r)!)

Fill in the known values.
(100!)/(4!(100-4)!)

Cancel out the common factorial factors.
(100*99*98*97)/(4*3*2)

Cancel out the remaining common factors.
25*33*49*97

Multiply 25 by 33 to get 825.
825*49*97

Multiply 825 by 49 to get 40425.
40425*97

Multiply 40425 by 97 to get 3921225.
3921225