How many 3-digit numerals end with a digit that represents a prime number?  Choose the most appropriate option:
A) 16
B) 80
C) 160
D) 180
E) 400

Rationale: "prime digits 2 , 3,5 and 7 . three digit numbers _ _ _ 1 st place can be filled in 4 ways 2 nd place can be filled in 10 ways 3 rd place can be filled in 10 ways total = 4 * 10 * 10 = 400 ans : e"
Answer: E