Calling on text from a cell within a function

Hey everyone,

I have to make these sheets for work to keep track of daily gigabyte totals from cameras. Everyday I create a new sheet and call upon the last sheet to create totals to date. This is the current function:

=E36+'Day 8'!N36

Now I also have a cell that has the current day. So cell H3 contains: 8

Is there a way so that I can rewrite the function to do the math I need it to do automatically if I only change the contents of H3. Right now I am having to go through 16 cells to manually change 'Day #' to the next day.

Thanks!

Uh oh, I forgot to mention that I need the H3 cell to be one less from the pervious. So if Today is Day 7 and I need it to call upon Day 6 I need it to subtract 1 somehow.