一道SAT数学题,不太明白题的意思
问题描述:
一道SAT数学题,不太明白题的意思
a snack machine has buttons arranged as shown above.if a selection is made by choosing a letter followed by a one-digit number,what is the greatest number of different selections that could be made?
A D 1 4 7
B E 2 5 8
C F 3 6 9
答
快餐机器按钮安排如上所示.如果一个选择是由选择一个字母,紧随其后的是一个一位数号码,则最多有几种选择?
答案是54
排列组合的小问题
要求选一个字母和一个数字,不考虑顺序,那就是6*9=54种情况