Mismatched Units

Stores can quietly break the comparison by labeling sizes in different units. One paper-towel pack lists a price per roll; another lists price per 100 sheets. Per roll looks cheaper until you notice the rolls hold different sheet counts.

Convert both to the same unit before judging. A 2-roll pack at $2.99 (110 sheets each) is about $1.36 per 100 sheets. A 6-roll pack at $7.49 (60 sheets each) is about $2.08 per 100 sheets. Same product, and the small pack wins once the units match.

Round And Compare

You rarely need the price to the penny. Round the numbers and the math happens in your head. $3.50 for a dozen is roughly $0.29 each. $5.00 for 20 is $0.25 each.

That is close enough to call a winner without a calculator. Save the precise division for when two options land neck and neck.