计算2+4+6+8+10+12+14+16+18+20.
问题描述:
计算2+4+6+8+10+12+14+16+18+20.
答
2+4+6+8+10+12+14+16+18+20,
=(2+18)+(4+16)+(6+14)+(8+12)+20+10,
=20+20+20+20+20+10,
=20×5+10,
=100+10,
=110.