Q. Sum of all the odd divisors of 720 is
A) 76
B) 78
C) 80
D) 84
Explanation
(b)
$\because 720 = 2^{4} \times 3^{2} \times 5^{1}$
$\therefore$ Sum of all odd divisors $= (1 + 3 + 3^{2})(1 + 5^{1})$
$= 13 \times 6 = 78$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.