求一个小数的近似数时，常用 法保留小数位数．
12m的是 m，50元是 元的．
×= ÷=0.2× =25× =1．
12个是 ，27×=27÷ × ．
4×=÷3=====
×= ÷=0.5× =15× =1．
是 m，50元是 元的
．
= ÷
=0.2× =25× =1．
是 ，27×
=27÷ × ．
=
÷3=
=
=
=
=
= ÷
=0.5× =15× =1．
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