1+1+2+3+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+…………10000000000

问题描述:

1+1+2+3+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+…………10000000000

1+1000000000(1000000000+1)/2 =500000000500000001