Complete the series.
2, 6, 12, 20, 30, 42, 56, (…)

Correct option is D

Given:
2, 6, 12, 20, 30, 42, 56, (…)
Identification of logic:
first term is = 2 + 4 = 6
second number = 6 + 6 = 12
we can say difference is consecutive 4, 6, 8, ……..
logic: difference is – 4, 6, 8, 10, 12, 14, 16
application of logic:
third number = 12 + 8 = 20
similarly,
20 + 10 = 30
30 + 12 = 42
42 + 14 = 56
56 + 16 = 72
finally we got the missing number is ? = 72.