cell 1 passing data to cell 2 then cell 1 reverts back to 0 while cell 2 maintains sum

I need some help please

I need to be able to enter data (numbers) in cell 1 and then have that data passed to cell 2 (adding to the total in cell 2)

Then have cell 1 revert back to the value of 0 while cell 2 keeps the updated sum

for example


cell 1 cell 2
0 5

then 2 is entered into cell 1

cell 1 cell 2
2 7

then have cell 1 revert back to 0 while cell 2 keeps its total

cell 1 cell 2
0 7


Is there anyone that knows how to do this?