Question

Fill in the blank

$\begin{array}{ccc}12& 47& ....\\ 30& 3& 17\\ 5& 38& 8\end{array}$

Answer 1

First arrange the numbers in the ascending order and then take the difference.
You can observe that the differences are 2, 3, 4, 5, 13, 8 and 9
If the difference 13 is split into 2 parts as 6 and 7, then you observe that the differences are 2, 3, 4, 5, 6, 7, 8 and 9, which are in arithmetic progression with common difference 1.
So, the missing number is 17 + 6 = 23