How many three-digit numbers are there such that all three digits are differet
and the first digit is not zero?
A)504 B)648 C)720 D)729 E)810
答案是B
但我想问three-digit numbers的百位数可以是0吗?
我的想法是百位数和个位数都不能是0
所以是10*9*8-9*8*1-9*8*1=576
但是没有这答案，谁可帮忙解惑一下 感恩!