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
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