用彩笔描出如图的边线.
计算,能简便的要简便算.31.9×18﹣8×31.9 21÷(+)÷ ×14+ 7.8÷[32×(1﹣)+3.6].
混合运算.(写出计算过程)28.7﹣14.7÷1.4 0.25×4.56×40 (1.7+3.3÷5)×0.20.45+0.15×997 12×0.25+8.8×2.5 (3﹣1.6)÷2.5×0.1.
计算下面各题,能简算的要简算.①4.28﹣1.39﹣2.61 ②7.2×0.3+0.3×0.8 ③0.4×3.14×2.5 ④9.4×[3.6÷(5.4÷0.9)]⑤840÷(0.23+0.37)÷7 ⑥23.7╳1.25╳8 ⑦12.5×102 ⑧9.1+0.9╳(22﹣18.7)
计算下面各题.(能简算的要简算)38×7.3+27×3.8 32×1.25×0.25 4.5×(10.5﹣12.06÷1.5) 38.75﹣(24.5+8.75)
计算.(能简算的要简算)①0.25×6.82×4 ②1.344+0.162÷4③12.68﹣4.8﹣3.68 ④3.6÷1.2﹣0.8×2.7⑤9.2×1.05÷3.4 ⑥(2.6+3.2÷1.28)÷1.7(得数保留两位小数)⑦6.83×(3.8﹣2.3)+1.5×3.7 ⑧4.5×[7.68÷(8.2﹣1.8)].