3.52乘0.79减0.173乘7.9加1.79乘0.21

3.52x0.79-0.173x7.9+1.79x0.21=0.79x（3.52-1.73）+1.79x0.21=0.79x1.79+1.79x0.21=1.79x(0.79+0.21)=1.79x1=1.79

3.52乘×0.79-0.173×7.9+1.79×0.21
=3.53×0.79-1.73×0.79+0.79×0.21+0.21
=0.79×（3.53-1.73+0.21）+0.21
=0.79×2.01+0.21
=0.79×（2+0.01）+0.21
=0.79×2+0.0079+0.21
=1.7979

(3.52*0.79)-(0.173*7.9)+(1.79*0.21)=1.79

3.52×0.79-0.173×7.9+1.79×0.21
=3.53×0.79-1.73×0.79+0.79×0.21+0.21
=0.79×（3.53-1.73+0.21）+0.21
=0.79×2.01+0.21
=0.79×（2+0.01）+0.21
=1.7979 (用简便方法做的)