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
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