Question

next number in sequence 1, -2, 5, 2, 9, 6, 13 ?

Answer 1

1, -2: To go from 1 to -2, subtract 3
-2, 5: To go from -2 to 5, add 7
5, 2: To go from 5 to 2, subtract 3
2, 9: To go from 2 to 9, add 7
Now look at the pattern of going from one number to the next one starting at 1:
-3, + 7, - 3, + 7