Find the sum of all odd factor of 840

Find the sum of all odd factor of 840.

a) 182

b) 192

c) 162

d) 172

Sol:

840 = 2³ × 3 × 5 × 7

Sum of all odd factors of 840

= (2⁰).(3⁰+3¹).(5⁰+5¹).(7⁰+7¹)

= 1 × 4 × 6 × 8

= 192