Cody saved $5 in the first week and increased his savings by $4 each week. How much would he have saved at the end of 9 weeks?
Make a list: 5, 9, 13, 17, 21, 25, 29, 33, 37
Using rainbow method: 5 + 37 = 429 + 33 = 4213 + 29 = 4217 + 25 = 42Sum of each pair = 42Number of pairs: 4, left: 21 Sum of all pairs = [42 x 4] + 21 = 168 + 21 = $189 Answer(s): $189
