Question

question 1 of 5
which of the following numbers is not a factor of 156 ?
a 3
b 4
c 8
d 12

Explanation:

Step1: Check if 3 is a factor

To check if 3 is a factor of 156, we use the divisibility rule for 3: the sum of digits of 156 is \(1 + 5 + 6 = 12\), and 12 is divisible by 3. So, \(156\div3 = 52\), which is an integer. Thus, 3 is a factor.

Step2: Check if 4 is a factor

A number is divisible by 4 if its last two digits form a number divisible by 4. For 156, the last two digits are 56, and \(56\div4 = 14\). Also, \(156\div4 = 39\), an integer. So, 4 is a factor.

Step3: Check if 8 is a factor

A number is divisible by 8 if its last three digits form a number divisible by 8. For 156, \(156\div8 = 19.5\), which is not an integer. So, 8 is not a factor. (We can also check the other option for completeness, but since we found the non - factor, we can conclude here. For 12: \(156\div12 = 13\), an integer, so 12 is a factor.)

Answer:

C. 8