在5.4、5.40、5.400这三个数中5.400最大. . (判断对错)
:12=:=0.3÷ == %
=5:8= %= ÷32=0.625.
4÷ == :15== %=( 小数)
12: ==0.6=48÷ .
:30=30÷ === (小数)= 折.