2元最少买3样
2 X 3 = 6
4 X 12 = 48
6 X 1 = 6
6元最多买5样
2 X 7 = 14
4 X 4 = 16
6 X 5 = 30
(本人头脑比较单纯,花了一支烟的工夫才找到用什么方法来计算)