查人人中国名人网罗马黑帮 影音先锋:8.4*0.4+1.6*7.9 简便运算方法
来源：百度文库 编辑：查人人中国名人网 时间：2024/05/07 04:36:04
=(7.9+0.5)*0.4+1.6*7.9
=7.9*0.4+7.9*1.6+0.5*0.4
=7.9*（0.4+0.6）+0.5*0.4
=……
应该会了吧
8.4×0.4+1.6×7.9
=2.1×4×0.4+1.6×7.9
=2.1×1.6+1.6×7.9
=（2.1+7.9）*1.6
=10*1.6
=16
8.4*0.4+1.6*7.9
84*4+16*79
=16*21+16*79
=16*(21+79)
=1600
8.4*0.4+1.6*7.9=16
用计算器算
原式＝2.1*4*0.4+1.6*7.9
=2.1*1.6+1.6*7.9
=1.6*(2.1+7.9)
=1.6*10
=16
够简便了吧
8.4*0.4+1.6*7.9
=8.4*(0.5-0.1)+1.6*(8.0-0.1)
=8.4*0.5-8.4*0.1+1.6*8.0-1.6*0.1
=4.2+12.8-0.84-0.16
=17-1
=16