5.04999用四舍五入法保留一位小数，就是5.1． ．
把小数化成分数，把分数化成小数． 0.05= = = 0. ．
=0.75=6： = %= 折．
将45%化成小数后应为 ．
1： ==25÷ = %
= = 折= （填小数）．
= 
= 0.
．
=0.75=6： = %= 折．
=25÷ = %
= = 折= （填小数）．
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