Logic

[masthead]

Which of the numbers 3-7-8-15-30 does not belong in the following series, and why?
2-3-6-7-8-14-15-30

[Dinkypuzzled]

8.
The sequence goes - add one, double it ......

[Gizmonster]

The problem has been solved by Dinkypuzzled, but if the puzzle was re-worded so that more than 1 number didn't belong in the series, then the following works too:

The numbers 3, 7, 8 and 15 can be removed so the series now reads:

2, 6, 14, 30 ....

the next number is determined by multiplying the previous number by 2 and then adding 2

(2 x 2) + 2 = 6
(6 x 2) + 2 = 14
(14 x 2) + 2 = 30 .....
.....

[masthead]

Well done chaps...good answers!