Find the missing number in the following series:
43, 172, 86, 344, ?

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
ABC, DYF, GVI, ?

In the following question, select the odd number pair from the given alternatives.
5, 11, 21, 43, 85, ?

. ____, 9, 25, 49, 121, 169

What value will come in place of question mark (?) in the number – series given below?

37 74 77 154 157 ? 

2, 9, 30, ?, 436, 2195, 13182

3, 4, 7, 11, 18, 29, ?

In following question, a sequence is given, with one term missing. Choose the correct alternative from the given ones that will complete the series.
7, 12, 22, 42, 82, ?