Question

Вычислите рациональным способом: 

1) 8.3*7+4.5*7+1.7*7+5.5*7=
2) 0.85*4+0.73*5+0.15*4+0.27*5=
3) 5.25*2+6.31*3+2*0.75+3*0.69=
4) 9.75*10+0.07*100+0.25*10+0.03*100=

Answer 1

$1),...=0.1cdot7(83+45+17+55)=0,1cdot 7cdot200=140$

$2),...=0.04cdot(85+15)+0.05cdot(73+27)=0.04cdot100+0.05cdot100=\ \ =4+5=9$

$3),...=0,02cdot(525+75)+0.03cdot(631+69)=\ \ =0.02cdot 600+0.03cdot700=12+21=33$

$4),...=0.1cdot(975+25)+100cdot(0.07+0.03)=\ \ =0.1cdot 1000+100cdot 0.1=100+10=110$