A number is divisible by 2 if the last digit is 0, 2, 4, 6 or 8. 168 is divisible by 2 since the last digit is 8. ... 168 is divisible by 3 since the sum of the digits is 15 (1+6+8=15), and 15 is divisible by 3. A number is divisible by 4 if the number formed by the last two digits is divisible by 4.