How many 4-digit numbers that are divisible by 4 can be formed using the digits 1, 2, 3 and 4 (repetition of digits is not allowed)?

Step-by-step solution

A number is divisible by 4 if the number formed by its last two digits is divisible by 4 . Using the digits 1, 2, 3, 4 without repetition, the possible two-digit numbers at the end that are divisible by 4 are 12, 24 , and 32 . For each of these endings, the remaining two digits can be arranged in the first two places in 2! = 2 ways. Total number of such 4 -digit numbers is 3 2 = 6 . Answer: 6