个是;1的分数单位是 ,再加上 个这样的分数单位就是最小的质数.
20: =0.8==24÷ = %.
=8÷ = :20=0.25.
=15÷ = ÷30=七五折= %
6: == %= ÷32.
1.5=18÷ == :6= %