5, 9, 17, 29, 45, ... ?

Answer: Option C

Explanation:

Patten is +2, +4, +4, .., .., +16, +16

Missing number will be 18+8 = 26

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 B

Explanation:

Pattern is +5, +10, + 15, +20

Next number in the series will be 56 + 25 = 81

Answer: Option C

Explanation:

\begin{aligned}
\text{Pattern is }\\
+1^2-1, +2^2-1, +3^2-1,+4^2-1 \\
5^2-1 = 28 + 24 \\
= 52
\end{aligned}

Answer: Option C

Explanation:

In this series the pattern is +4, +8, +12, +16, so next will be +20

Term which will replace the question mark in this series will be 45+20 = 65