简便计算×34.5×8.23-34.5+2.77×34.519.98×37-199.8×1.9+1998×0.82314×0.043+3.14×7.2-31.4×0.153.9×1.2+0.1275×4.7+15.9×257.5×23+31×2.512×69+53×3.1+72×3.10.79×0.46+7.9×0.24+11.4×0.079对不起咯~第7题错了~应该是12.5×69+53×3

Answer 1

34.5×8.23-34.5+2.77×34.5
=34.5*（8.23-1+2.77）
=34.5*10=345
19.98×37-199.8×1.9+1998×0.82
=19.98*37-19.98*19+19.98*82
=19.98*(37-19+82)=19.98*100=1998
314×0.043+3.14×7.2-31.4×0.15
=3.14*4.3+3.14*7.2-3.14*1.5
=3.14*(4.3+7.2-1.5)=3.14*10=31.4
3.9×1.2+0.12
=3.9*1.2+0.1*1.2
=(3.9+0.1)*1.2=4*1.2=4.8
75×4.7+15.9×25
=25*3*4.7+15.9*25
=25*(14.1+15.9)
=25*30=750
7.5×23+31×2.5
=2.5*3*23+31*2.5
=2.5*(69+31)
=2.5*100=250
12×69+53×3.1+72×3.1这题有误
应该是12.5×69+53×3.1+72×3.1
=125*6.9+(69+72)*3.1
=125*(6.9+3.1)=125*10=1250
0.79×0.46+7.9×0.24+11.4×0.079
=0.79*0.46+0.79*2.4+1.14*0.79
=0.79*(0.46+2.4+1.14)=0.79*4=3.16
累死了 - -