用简便运算 0.25X9.7X0.04 29.8X12.5X0.8 0.28X8X0.04X12.5 0.28X31.7X4 8.4X0.78+1.6X0.78 0.53X101

0.25*4*9.7*0.04/4=9.7*0.01=0.0097
29.8*12.5*8=29.8*0.125*8*10=29.8*100=2980
0.28*8*0.125*100*0.04=0.28*1*4=1.12
0.28*31.7*4=1.12*31.7=35.504
8.4*0.78+1.6*0.78=0.78*(8.4+1.6)=0.78*10=7.8
0.53*101=0.53*100+0.53*1=53+0.53=53.53

0.25*4*9.7*0.04/4=9.7*0.01=0.0097
29.8*12.5*8=29.8*0.125*8*10=29.8*100=2980
0.28*8*0.125*100*0.04=0.28*1*4=1.12
0.28*31.7*4=1.12*31.7=35.504
8.4*0.78+1.6*0.78=0.78*(8.4+1.6)=0.78*10=7.8
0.53*101=0.53*100+0.53*1=53+0.53=53.53 好了

主要运用到：25X4=100 125X8=1000 a（b+c）=ab+ac
1、0.25X9.7X0.04=0.25X0.04X9.7=0.01X9.7=0.097
2、29.8X12.5X0.8=29.8X10=298
3、0.28X8X0.04X12.5=0.28X0.04X100=0.28X4=1.12
4、 0.28X31.7X4=1.12X31.7=35.504
5、 8.4X0.78+1.6X0.78=0.78X(8.4+1.6)=0.78X10=7.8
6、 0.53X101=0.53X(100+1)=53+0.53=53.53

〔12.5+0.25〕X80＝12.5X80+0.25X80＝100+20＝120