784070+78407.1+7840.72+784.073+78.407==

784070+78407.1+7840.72+784.073+78.407==
784070+78407.1+7840.72+784.073+78.407
=
=

784070+78407.1+7840.72+784.073+78.407==
784070+78407.1+7840.72+784.073+78.407
1.设784070=a,则
原式=a+[(a+1)/10]+[(a+2)/100]+[(a+3)/1000]
+(a/10000)=
(10000a+1000a+1000+100a+200+10a+30+a)/1000
0=
(11111a+1230)/10000
将a=784070代入,得
原式=871180.3