Question
Question: The number of proper divisors of 1800 which are also divisible by 10, is...
The number of proper divisors of 1800 which are also divisible by 10, is
A
18
B
34
C
27
D
None of these
Answer
18
Explanation
Solution
1800 = 23 × 32 × 52
∴ The required number of proper divisors = total number of selections of at least one 2 and one 5 from 2, 2, 2, 3, 3, 5, 5
= 3 × (2 + 1) × 2 = 18