计算:|1/21-1/20|+|1/22-1/21|+|1/23-1/22|...|1/30-1/29|

问题描述:

计算:|1/21-1/20|+|1/22-1/21|+|1/23-1/22|...|1/30-1/29|

=1/20-1/21+1/21-1/22+1/22-1/23+......+1/29-1/30
=1/20-1/30
=1/60

1/21