Completing Series

1. Complete the series: 2, 4, 6, 8, ?
   Answer: 10
2. Complete the series: 5, 10, 15, 20, ?
   Answer: 25
3. Complete the series: 1, 4, 9, 16, ?
   Answer: 25
4. Complete the series: 2, 3, 5, 7, ?
   Answer: 11
5. Complete the series: 3, 6, 9, 12, ?
   Answer: 15
6. Complete the series: 8, 16, 32, ?
   Answer: 64
7. Complete the series: 1, 3, 6, 10, ?
   Answer: 15
8. Complete the series: 10, 20, 30, 40, ?
   Answer: 50
9. Complete the series: 0, 2, 4, 6, ?
   Answer: 8
10. Complete the series: 9, 18, 27, ?
    Answer: 36
11. Complete the series: 7, 14, 21, ?
    Answer: 28
12. Complete the series: 11, 22, 33, ?
    Answer: 44
13. Complete the series: 1, 8, 27, ?
    Answer: 64
14. Complete the series: 4, 8, 12, 16, ?
    Answer: 20
15. Complete the series: 3, 6, 12, 24, ?
    Answer: 48