下麵各題,怎樣簡便就怎樣計算. 算式:1、0.76x4.2+3.1x4 2、290.7-22.78÷3.1-33 3、1.4x8.6+8.6x8.6 4、0.24x2.5x12.5

下麵各題,怎樣簡便就怎樣計算. 算式:1、0.76x4.2+3.1x4 2、290.7-22.78÷3.1-33 3、1.4x8.6+8.6x8.6 4、0.24x2.5x12.5


1、0.76x4.2+3.1x4=3.192+12.4=15.5922、290.7-22.78÷3.1-33=290.7-7.348-3=250.3523、1.4x8.6+8.6x8.6=8.6*(1.4+8.6)=864、0.24x2.5x12.5=0.4x2.5x12.5x0.6=1x7.5=7.5



下麵各題怎樣算簡便就怎樣算
0.85*101-0.85 3.6/4-0.12*5(3.95-3.68)/9 4.8*5-6.6


0.85*101-0.85
=0.85*(101-1)
=0.85*100
=85
3.6/4-0.12*5
=0.9-0.6
=0.3
(3.95-3.68)/9
=0.27/9
=0.03
4.8*5-6.6
=4.8*10/2-6.6
=48/2-6.6
=24-6.6
=17.4