1.1998+1997+1996-1995-1994-1993+1992+1991+1990-1989-1988-1987+…………+204+203+202-201-200-199=(1998-1995)+(1997-1994)+(1996-1993)+(1992-1989)+(1991-1988)+(1990-1987)…………+(204-201)+(203-200)+(202-199)=3+3+3+3+3+3……………………
+3+3+3(总共900个3)=2700
2 6.25*0.16+264*0.0625+5.2*6.25+0.625*20
=6.25*0.16+264*0.01*6.25+5.2*6.25+6.25*0.1*20
=6.25*0.16+2.64*6.25+5.2*6.25+6.25*2
=6.25*(0.16+2.64+5.2+2)
=6.25*10
=62.5
第二题题目好像错了哈