简便计算
①70.8﹣1.25﹣1.75 ②5.81+8.3+4.19+11.7 ③3.54×0.29﹣0.29×2.54
④0.25×17.3×0.4 ⑤7.2×9.9 ⑥48×0.69+3.1×4.8．
简便计算
①70.8﹣1.25﹣1.75 ②5.81+8.3+4.19+11.7 ③3.54×0.29﹣0.29×2.54
④0.25×17.3×0.4 ⑤7.2×9.9 ⑥48×0.69+3.1×4.8．
，文艺书相当于全部书的
，其中科技书有250本，阅览室里共有多少本书？
= 4
= 6﹣1
= 4
= 1
=
=
= 5
=
=
= 4.5﹣
=
=
=
÷10=
×
×
=
×
=
÷
= 6×
=
×9×
= 5÷
÷5=
÷2=
÷
= 6×
=
×2=
=
×
= 18÷
= 3﹣
=
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