Question

You are stacking soup cans for a display in a grocery store. Your manager wants you to stack 120 cans in layers, with each layer after the first having one less can then they layer before it. One can should be in the top layer. If you use all 120 cans, how many cans should be in the first layer?

Answer 1

arithmetic sequence
first term is one so a = 1
d = -1
sum =120
see
http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html