Bathroom tissue is expensive, and everyone needs to pinch their pennies when they pinch off a loaf. Cell phone calculators don't have enough precision to calculate the per-unit cost of toilet paper. They also lack parentheses to do some necessary grouping to calculate:

PRICE / ( SHEETS PER ROLL * ROLLS )

Solution is below the fold.

To get around this, do this:

PRICE x 100 / SHEETS / ROLLS

Where PRICE x 100 is just the price without the decimal point before the "cents" portion. So, if the package costs $16.99, you enter "1699".

If there are 36 rolls and 350 sheets per roll, you enter "/ 36 / 350" and click "=". Again, that's:

1599 / 36 / 350