Okay, the first step is to find what number is added up to 7 for instance, to make 16 and so on. To find that you ask yourself what number plus 7 equals 16. The answer to that would be 9.
Lets add up the numbers,
7 + 9 = 16
16 + 9 = 25
25 + 9 = 34
34 + 9 = 43
43 + 9 = 52
52 + 9 = 61
61 + 9 = 70
70 + 9 = 79
79 + 9 = 88
When you're constantly counting how much numbers you've went through, then you'll find that you have found the 9th number of your question.
