5,9,17,29,45, ?

Answer: Option C

Explanation:

Pattern is *2, *3, *4
So next number is the series will be *5
24*5 = 120

Answer: Option A

Explanation:

We can judge that it is A.P.
With 6 as difference
nth term in A.P. = a+(n-1)d
a= 3, n = 21, d = 6
So, 21st term will be = 3+(20)6 = 123

Answer: Option C

Explanation:

Please note that above sequence is containing 3 series
Series 1 : 8, 7, 6, (..)
Series 2 : 9, 10, 11, 12
Series 3 : 8, 9, 10

In series 1 pattern is -1. So missing term will be 6-1 = 5

Answer: Option A

Explanation:

Pattern is +5, +10, +15, + 20. So next will be 56+25 = 81

Answer: Option D

Explanation:

Series is having pattern
\begin{aligned}
3*1^2, 3*2^2, 3*3^2, ......\\
\text{Next will be } 3*7^2 = 147
\end{aligned}