Question

Which number will replace the question mark in the series : 1 , 3 , 10 , 24 , 64 , 129 , ? , 777

Answer 1

Here, first term=1; second term=3
Therefore common difference= t2-t1
= 3-1
=2
Now, t7=a+6d
= 1+6(2)
= 1+12
=13
Therefore ? = 13.