1X2十2X3十3X4十4X5十···十98X99十99X100=2X（1+3）+4X（3+5）+6X（5+7）+。。。+98X（97+99）+99X100=8X(1X1+2X2+3X3+4X4+5X5+6X6+7X7+。。。+49X49)+99X100=8X1/6X49X（49+1）X（2X49+1）+99X100=8X1/6X49X50X99+99X100=323400+9900=333300
