add 37 to all numbers to make first number 1.
1, 8, 15, -------- 147. Pattern is adding 7 everytime. So, 147/7= 21. Remember, everytime you count a list, like {1,2,3,4,5,6,7,8,9}, you have to add 1. 9-1+1=9 numbers. So, 21+1=22, like CPhill (the pro) says.
