Question

Select the number of brick piles that cannot be divided into any number of boxes except for 1 and itself.

• A. 15
• B. 19
• C. 10
• D. 14

Answer 1

The correct option is B 19

We have to find the prime numbers.
The factors of the numbers are-
15 = 1, 3, 5 and 15
19 = 1, 19
10 = 1, 2, 5, 10
14 = 1, 2, 7 , 14
So, 19 brick piles cannot be divided into any number of boxes except for 1 and itself.