Question

Look at this series: 4, 7, 25, 10, __, 20, 16, 19, ... What number should fill the blank?

Answer 1

4,7,25
10,_,20
16,19,_
see the second space in all three
you will see 7+6=13
13+6=19
now in last space
25-5=20
20-5=15

Answer 2

first blank will be13