0.4小时= 分 18.9÷0.04= ÷4.
2的倒数是 ;0.6与 互为倒数;最小合数的倒数是 ; 的倒数是0.5.
× = ×= × =1.
35× =0.5× =× =6÷ =1.
任何一个数(零除外)与它的倒数的乘积是1. .
× =× =× =9× =1.