Question

A student ID number is a letter of the alphabet followed by 2 digits. How many different IDs are possible if the digits can be repeated?

Answer 1

digits range from 0 to 9 That makes 10 double digits

number of permutation of 2 digits when they are different = 10*9 = 90

this gives 90 + 10 = 100 different ways to arrange the digits

combine this with e 26 letters in alphabet we get number different IDs

= 26*100 = 2600