計算:12+(13+23)+(34+24+14)+(45+35+25+15)+…+(1920+1820+…+120)=______.

計算:12+(13+23)+(34+24+14)+(45+35+25+15)+…+(1920+1820+…+120)=______.


12+(13+23)+(34+24+14)+(45+35+25+15)+…+(1920+1820+…+120),=12+1+112+2+…+912,=12+22+32+…+192,=(1+2+…+19)÷2,=(1+19)×19÷2÷2,=95.故答案為:95.