how many 4 digit numbers divisible by 4 can be made with digits 1 , 2 , 3 , 4 , 5 if the repetition of digits is not allowed ?  Choose the correct choice from the following choices:
A) 10
B) 20
C) 30
D) 40
E) 50

Rationale: a number is divisible by 4 if the last 2 numbers are divisible by 4 ( divisible by 2 twice ) ending can be 12 24 32 42 52 case : ending with 12 , 24,32 , 42,54 first digit - 3 choices second digit - 2 choices third digit - 1 choice fourth digit - 1 choice 6 possible choices for each ending ( e . g . 3412,3512 , 3212 , 4512 , 5312 , 5412 ) total number of 4 digit numbers divisible by 4 = 6 * 5 = 30 answer : c
Answer: C