724*999=724*(1000-1)=
=724*1000-724*1=
=724000-724=723276
380*999=380*(1000-1)=
=380*1000-380*1=
=380000-380=379620
405*999=405*(1000-1)=
=405*1000-405*1=
=405000-405=404595
657*999=657*(1000-1)=
=657*1000-657*1=
=657000-657=656343
813*999=813*(1000-1)=
=813*1000-813*1=
=813000-813=812187
678*999=678*(1000-1)=
=678*1000-678*1=
=678000-678=677322
