Question

what is the next no in the series 7,9,27,5,7,21,11,13,39,3,5,...?

Answer 1

(1)

7 + 2 = 9

9 * 3 = 27




(2) 

5 + 2 = 7

7 * 3 = 21




(3) 

11 + 2 = 13

13 * 3 = 39



(4) 

3 + 2 = 5

5 * 3 = 15


Therefore the next number is 15.


Hope this helps!