What number is missing from this series?
(series = a group or a number of related or similar things)
(series = a group or a number of related or similar things)
1, 3, 7, ? , 21
.
.
.
.
.
.
.
.
.
 |
| Let’s think about this…. |
.
.
.
.
.
.
.
.
.
.
the answer
.
.
.
.
.
.
.
.
.
.
.
.
.
are you sure?
.
.
.
.
.
.
.
.
.
.
.
.
.
The answer is 13!
1+2=3
3+4=7
7+6=13
13+8=21
3, 7, 13, 21
