I believe that your cells are formatted in scientific notation.
What you described appears to be in the neighborhood of
-10,000
When you click in the cell, you should see a recognizable number in the
formula bar.
Click in the cell, then <Format> <Cells> <Number> tab,
And see what you have formatted for that particular cell.
Format all your cells to either "General" or "Number".
Also, in your formulas, the "+" sign and the parenthesis are unnecessary.
=E180-E179
is a perfectly legitimate formula.
Just had another thought.
Open a brand new sheet and type:
1234567890
Then <Enter>.
Now, drag the column width very slightly narrower.
You should see the number change to scientific.
If not, drag it ever so slightly narrower again until it does change.
Once you see the scientific notation, continue the narrowing of the column
and you'll eventually see the display change to the more familiar lb. signs,
which usually signifies a too narrow column of numbers.
The double display change usually occurs when a cell is originally formatted
to "General", as a new sheet usually is.
So, check the width of your columns on your original sheet if their format
appears to be OK (general).