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7.8*80+6.5和0.85*0.5+0.25*3的简便算法

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/07/19 19:57:07
7.8*80+6.5和0.85*0.5+0.25*3的简便算法
7.8*80+6.5
=1.3*5*6*16+6.5
=6.5*(96+1)
=6.5*97
=6.5*(100-3)
=6.5*100-6.5*3
=650-19.5
=630.5
0.85*0.5+0.25*3
=0.85*0.5+0.5*0.15
=(0.85+0.15)*0.5
=1*0.5
=0.5
再问: 0.5*0.15不等于0.25*3
再答: 7.8*80+6.5 =1.3*5*6*16+6.5 =6.5*(96+1) =6.5*97 =6.5*(100-3) =6.5*100-6.5*3 =650-19.5 =630.5 0.85*0.5+0.25*3 =0.25*1.7+0.25*3 =0.25*(1.7+3) =0.25*4+0.25*0.7 =1+0.175 =1.175 看错小数点了