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.
The Number Which Best Completes The Sequence Of 2 9 5 13 10 19 17?
27
First differences are
7 -4 8 -3 9 -2
One would expect the next first difference to be 10. Thus the next number is expected to be
17 + 10 = 27.
7 -4 8 -3 9 -2
One would expect the next first difference to be 10. Thus the next number is expected to be
17 + 10 = 27.