巧算20+11+12+...30?

2025-06-26 12:01:42
推荐回答(1个)
回答1:

20+11+12+……+30
=20+(11+19)+(12+18)+(13+17)+(14+16)+15+30
=20+30+30+30+30+30+15
=30×6+5
=185