2-1+4-3+6-5+8-7+10-9+1

17 查阅

2-1+4-3+6-5+8-7+10-9+12-11

参考答案:

2-1+4-3+6-5+8-7+10-9+12-11

=(2-1)+(4-3)+(6-5)+(8-7)+(10-9)+(12-11)

=1+1+1+1+1+1

=6