27×3.4+15.4×34+340×8%
=34*2.7+34*15.4+34*0.8
=34*(2.7+15.4+0.8)
=34*18.9
=34*(20-1.1)
=680-37.4
=642.6
1/2003+2/2003+3/2003+……+2002/2003
=(1+2+3+4+5+6+7……+2002）/2003
=（1+2002）/2003+（2+2001）/2003……+（1001+1002）/2003
=（1+2002）/2003*1001
=1001