1+2+3+4+5+6+7+8+9+10+11+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30...+1000=?
问题描述:
1+2+3+4+5+6+7+8+9+10+11+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30...+1000=?
答
=500500
答
500500
答
1000*499+1000+500=500500
答
(1+1000)/2*1000=500500