The difference between 2 and 9 is 7. The difference between 9 and 5 is 4. So 2+7=9. 9-4=5. 5+8=13. 13-3=10. 10+9=19. 19-2=17. This means that the next number would be 27, as 17+10=27.

27

First differences are

One would expect the next first difference to be 10. Thus the next number is expected to be

17 + 10 =

**7**-4**8**-3**9**-2One would expect the next first difference to be 10. Thus the next number is expected to be

17 + 10 =

**27**.