5年级数学题18.9*178.178+0.49-17.8*189.189=?3.42*76.3+76.3*5.76+9.

1个回答

  • [1] 18.9*178.178+0.49-17.8*189.189

    =18.9*17.8*10.01+0.49-17.8*18.9*10.01

    =0.49

    [2] 3.42*76.3+76.3*5.76+9.18*23.7

    =76.3*(3.42+5.76)+9.18*23.7

    =76.3*9.18+9.18*23.7

    =9.18*(76.3+23.7)=918

    [3] 12.5*3.79+1.25*31.7+125*0.304

    =12.5*3.79+12.5*3.17+12.5*3.04

    =12.5*(3.79+3.17+3.04)

    =125

    [4] 11.4*1.7+9.1*1.7-5*1.7+4.5*1.7

    =1.7*(11.4+9.1-5+4.5)

    =34

    [5] 6*13+4.8*18-1.2*37

    =6*13+6*0.8*18-6*0.2*37

    =6*(13+0.8*18-0.2*37)

    =6*20

    =120