Question

15．口算

4.7+2.3=	4.2×2=	6.05-2.5=	1.2×0.8=
1.4×0.5=	0.75×100=	0.02×0.5=	3.6÷0.3=
56÷100=	0.75÷0.25=	0.125×8=	0.56÷28=
10÷20=	302=	3.08÷0.01=	0.51÷17=
1÷4=	0.25×3.97×4=	0.7×0.7÷0.7×0.7=	9÷0.25÷4=

Answer 1

分析 根據(jù)整數(shù)和小數(shù)加減乘除法的計算法則計算即可求解．注意0.25×3.97×4變形為0.25×4×3.97計算，0.7×0.7÷0.7×0.7變形為（0.7×0.7）×（0.7÷0.7）計算，9÷0.25÷4關(guān)鍵除法的性質(zhì)計算．

解答 解：

4.7+2.3=7	4.2×2=8.4	6.05-2.5=3.55	1.2×0.8=0.96
1.4×0.5=0.7	0.75×100=75	0.02×0.5=0.01	3.6÷0.3=12
56÷100=0.56	0.75÷0.25=3	0.125×8=1	0.56÷28=0.02
10÷20=0.5	302=900	3.08÷0.01=308	0.51÷17=0.03
1÷4=0.25	0.25×3.97×4=3.97	0.7×0.7÷0.7×0.7=0.49	9÷0.25÷4=9

點評 考查了整數(shù)和小數(shù)加減乘除法，關(guān)鍵是熟練掌握計算法則正確進(jìn)行計算．