Problem 121
How many three-symbol codes (letter-number-number) can be made from the letters S, P, Y, and two digits from the set {0, 1, 2, … , 9} without repetition?
Solution
There are three positions.
Total cases for first position (three letters) = 3
Cases for second position = 10
Cases for third position are = 9
Total symbols codes are = 3 
10 9 = 270