If Task A can be performed in any one of x ways, and if, after Task A is performed, Task B can be performed in any one of y ways, then the combination tasks, A followed by B, can be performed in x·y ways.
Arranging the letters in the name "FRED".
Four ways to pick the first letter, then three ways to choose the second letter, then two ways to choose the third letter: a total of 4·3·2 = 24 arrangements (in yellow below).
F 


R 


E 


D 
