一块长方形菜地，宽是5米，长是宽的2倍，若在它的四周围长方形菜地，四周围上篱笆．需要篱笆多少米？
口算小博士．×=÷2= 80%﹣20%= 4×25%+16×25%=×=×72%=×÷=×÷×=
直接写得数．×= 1÷= 4×60%= 0.875÷0.125= 0.25××4=÷2= 10÷=×3.6=（）2=÷×0=
口算：×= 45×=÷10= 0÷8= 5.4×=÷= 0.65×= 50%﹣0.05=
直接写出得数 1÷= 1﹣=÷= 48×12.5%=+=×=÷10= 5÷﹣÷5=
直接写得数．======
×
=
÷2= 80%﹣20%= 4×25%+16×25%=
=
×72%=
×
÷
=
×
÷
×
= 1÷
= 4×60%= 0.875÷0.125= 0.25×
×4=
÷2= 10÷
=
×3.6=（
）2=
÷
×0=
×
= 45×
=
÷10= 0÷8
=
=
÷
= 0.65×
= 50%﹣0.05=
= 1﹣
=
= 48×12.5%=
+
=
×
=
÷10= 5÷
﹣
=
=
=
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