2+4+6+8+10+12+14+16+18

23 查阅

2+4+6+8+10+12+14+16+18+20

参考答案:

2+4+6+8+10+12+14+16+18+20

=(2+18)+(4+16)+(6+14)+(8+12)+10+20

=20+20+20+20+10+20

=110