One fictional printing service charges 10 plus 2 per item. Another charges 3 per item with no fixed charge. Which total is smaller? The answer depends on how many items the example includes.
Calculate at two quantities
For five items, the first formula gives 10 + 2 × 5 = 20. The second gives 3 × 5 = 15. For twenty items, the totals become 50 and 60 respectively.
The comparison reverses because the fixed charge is paid once in this simplified example, while the difference between the per-item charges grows with quantity.
Find the meeting point
At ten items, both formulas give 30. You can check that result by substitution without needing to memorise a named formula.
Make a small table for nine, ten and eleven items. It shows the change more clearly than declaring one arrangement always cheaper.
Keep the example’s limits attached
These are invented prices with identical items, no taxes, no minimum quantities and no additional charges. A real quotation may include conditions that change the calculation, and cost alone does not establish quality or suitability.
Our guide to reading financial information with better questions offers a useful companion habit: list what a comparison holds constant before using its result. A neat piece of arithmetic is only as applicable as its stated assumptions.