Solution:
This is an alternating repetition series, in which a random number, 61, is interpolated as every third number into an otherwise simple subtraction series. Starting with the second number, 57, each number (except 61) is 7 less than the previous number.

Solution:
The correct pattern is × 2, - 2.......So, 48 is wrong and must be replaced by (26 × 2 - 2) i.e., 50.

Solution:
This is an alternating number subtraction series. First, 2 is subtracted, then 4, then 2, and so on.

Solution:
The term of the given series are numbers formed by joining together consecutive odd numbers in order i.e., 1 and 3, 3 and 5, 5 and 7, 7 and 9, 9 and 11...................So, missing term = number formed by joining 11 and 13 = 1113

Solution:
According to the given question:

Solution:
The pattern is × 2, × 3/2, × 2, × 3/2, × 2,.............So, missing term = 18 × 3/2 = 27

Solution:
The correct pattern is + 5, + 8, + 11, + 14, ............So, 47 is wrong and must be replaced by (32 + 14) i.e., 46