156, 40, 21, 22, 45, ?

What will come in the place of question (?) mark in following number series:

The correct option is 181.

To find the missing term in the given number series, let us analyze the pattern or relation between consecutive terms:

156, 40, 21, 22, 45, ?

Let us test a pattern involving multiplication by fractional/increasing numbers and subtracting/adding a constant or pattern sequence:

$156\times 0.25+1=39+1=40$

$40\times 0.5+1=20+1=21$

$21\times 1+1=21+1=22$

$22\times 2+1=44+1=45$

As observed, each term is obtained by multiplying the previous term by a multiplier that doubles each step (0.25, 0.5, 1, 2, 4) and then adding 1.

Therefore, the missing term is calculated as:

$45\times 4+1=180+1=181$

Hence, the number that comes in place of the question mark (?) is 181.