How to add a new calculated column

Question

HI, 

I want to add and an acumulative values in a new “Accumulative” Column from SUMA_PROFIT column, begins from last record.

 

for example:

 

 

 

last record value 1714703269481.14 + penultimate record value 1228973052365.97 and so...

 

Do i explained well??

 

Thank u MATES