Question

The sum of all positive integral divisors of 1800 is

• A. 15x13x124
• B. 15x26x31
• C. 15x26x124
• D. 15x13x31

Answer 1

Answer: (D)

15x13x31

Answer 2

Since 1800 = 2³ x 3² x 5²

Sum of divisors = $\left( \frac{2^{4} - 1}{2 - 1} \right)\mspace{6mu}\left( \frac{3^{3} - 1}{3 - 1} \right)\mspace{6mu}\left( \frac{5^{3} - 1}{5 - 1} \right)$

= 15 x 13 x 31