脱式计算，能简算的要简算．0.389×4×0.25 21.97÷5÷2 30.8×12.6﹣30.8×2.6 4.05÷0.81+2.4．
直接写得数 ①+= ②1﹣0.25= ③0.72÷0.6= ④125×8= ⑤25×17×4= ⑥13×10.2=
脱式计算，能简算的要简算． ①②③ ④⑤⑥15×4.6﹣46×0.5．
看谁算的又对又快．+=+=﹣=﹣= 1﹣=+=﹣= 1﹣=+=﹣=+=+=
看谁算得快． 1﹣﹣﹣+ 0.75+++0.25+0.625．
6﹣3﹣0.625．
+
= ②1﹣0.25= ③0.72÷0.6=
②
③
⑤
⑥15×4.6﹣46×0.5．
+
=
=
﹣
=
﹣
=
=
+
﹣
= 1﹣
=
+
=
﹣
=
+
=
+
=
﹣
﹣
+
+
+0.25+0.625．
﹣3
﹣0.625．
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