Explanation:
Each number is the proceeding number multiplied by -2.
So, the required number is -128.

The pattern is 1 x 2, 2 x 3, 3 x 4, 4 x 5, 5 x 6, 6 x 7, 7 x 8.
So, the next number is 8 x 9 = 72.

Explanation:
There are two series (8, 11, 14, 17, 20) and (7, 12, 17, 22) increasing by 3 and 5 respectively.

Explanation:
+11 =16
+33 =49
+55 =104
+77 =181

Explanation:
6 = 1^1 + 2^1 + 3^1
14 = 1^2 + 2^2 + 3^2
36 = 1^3 + 2^3 + 3^3
98 = 1^4 + 2^4 + 3^4
Thus the next number will be
1^5 + 2^5 + 3^5 = 276

Explanation:

A unique pattern has been made into use in this series.

All numbers are (n^3 + n^2) where n is 1, 2, 3 and so on.