Permutations & Combinations
Sum of odd divisors
MMTS_Full_Test_14
Grade 12

Question:

The sum of the odd divisors of $10!$ is
(A) 28008
(B) 29008
(C) 30008
(D) 32008

Step-by-Step Solution

Key Concept: Find prime factorization of $10!$. Sum of odd divisors = product of sums over odd primes only.
Sum of odd divisors $=\frac{3^5-1}{2}\cdot\frac{5^3-1}{4}\cdot\frac{7^2-1}{6}=121\times31\times8=30008$.
Correct Answer: (C) 30008

Master Permutations & Combinations with Mathbee

Practice this topic under real exam conditions with strict timers, or ask our AI Mentor to explain the concepts step-by-step.

Start Practicing for Free