Question 1025112
.
Please help me this problem is driving me crazy.

Write the sum using sigma notation: 

1/1⋅2+1/2⋅3+1/3⋅4+⋯+1/219⋅220=
A
∑ B
n=1
, where 

A=
       

B=
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


<pre>
A = 219.

B = {{{(1/n-1/(n+1))}}},
</pre>