12
You need to add 12.
You need to add 6 - (-9) = 6 + 9 = 15.
You need to add 7 (or +7)
Add 11 -6 + 11 = 5
17 - (-6) = 23 Therefore, the number you have to add to -6 to make 17 is 23.
9 - (-6) = 9 + 6 = 15
14
13
15
16
The next number would be 18.3, 4, 6, 9, 13To get from 3 to 4, you need to add one. To get from 4 to 6, you need to add two. To get from 6 to 9, you need to add three. And so on and so on.
9