THE NUMBERS, EXPLAINED
How to use this calculator.
Buy-c-get-d-free applies only to identical items at one price. Full groups receive free units; incomplete groups are charged normally. Quantity is fixed, so no extra items are added.
Start with your inputs
Enter identical item quantity, regular unit price, paid items per promotion group, free items per promotion group. Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Identical item quantity | 7 |
| Regular unit price | 5 |
| Paid items per promotion group | 1 |
| Free items per promotion group | 1 |
A worked example
With the example inputs above, free units is 3. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Free units | 3 |
| Charged units | 4 |
| Basket price | 20 |
How this is calculated
Free units
Count complete promotion groups and multiply by free units.
Charged units
Subtract free units from requested quantity.
Basket price
Multiply charged units by regular unit price.
Symbols and units
- a
- Identical item quantity
- b
- Regular unit price
- c
- Paid items per promotion group
- d
- Free items per promotion group
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
Buy-c-get-d-free applies only to identical items at one price. Full groups receive free units; incomplete groups are charged normally. Quantity is fixed, so no extra items are added.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Free units; Charged units; Basket price. The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Buy-c-get-d-free applies only to identical items at one price. Full groups receive free units; incomplete groups are charged normally. Quantity is fixed, so no extra items are added.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Further reading
OpenStax: Solve proportions and their applications ↗
Background reading; this does not imply endorsement or independent review of SumFizz.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
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