Solution:
In this addition series, 1 is added to the first number; 2 is added to the second number; 3 is added to the third number; 4 is added to the fourth number; and go on.

Solution:
The pattern is + 0.05, + 0.10, + 0.15,................ So, missing term = 0.8 + 0.20 = 1

Solution:
The pattern is × 3/2.So, missing number = 131/2 × 3/2 = 27/2 × 3/2 = 81/4 = 201/4.

Solution:
First Term = 5760. Second term = 5760 /2 = 2880. Third Term = 2880/3 = 960. Fourth term = 960/4 = 240. Fifth term = 240/5 = 48. So, Required term = 48/6 = 8.

Solution:
The correct pattern in the series is + 1110. So, 5686 is wrong and must be replaced by (4566 + 1110) i.e., 5676.

Solution:
This is an alternating addition series with repetition, in which a random number, 66, is interpolated as every third number. The regular series adds 2, then 3, then 2, and so on, with 66 repeated after each "add 2" step.

Solution:
Each term in the series, except the first two terms, is 2 more than the sum of the preceding two terms.So, missing term = (42 + 70) +2 = 114