How many odd factors does 210 have?

Question

(A) 3
(B) 4
(C) 5
(D) 6
(E) 8

Answer 1

Thomas' approach is great: E

Answer 2

First find the prime factors:

 

210 = 7 x 5 x 3 x 2 x 1

 

Odd factors are 1, 3, 5, 7, 35, 21, 15, 105