Find the number puzzle

Find the number puzzle

Find the number that will replace the Question mark

In the image you can see some random number series.
But there is a pattern to the numbers.
Can you identify the pattern and
find the number that will replace the question mark symbol ?

Hint : the number 7 at the end is not wrong, it is correct.

Click here for Answer

Answer : 12

Explanation:
27 and 45 point towards 18.
2+7+4+5 = 18
Similarly 21 and 36 will make
2+1+3+6 = 12
Hence 12 will replace question mark.