External Data from Web - after refresh add the old value to new value -HELP

[FLAWLESSKING]

Hi guys, i am fetching external data from web, the data is live numerical data which changes every 10 secs, basically if Cell A1 value is "1" and i refresh the new data of A1, the new fetched value is 2 as per the external data from web, NOW A1=2, NOW WHAT i want is to Add that old data i.e 1 and add it to new data received from web, i.e 2, which final should be equal to 3, i am thinking hard but with no solution, i am learning, pls help, thanks.

 

[Ombir]

Share the url from which you want to extract the data ?