Exact purchasing arithmetic
The default reference tickets are 949p, 367p and 995p, totalling 2311p. A confirmed merchandise-only credit of£23.11 leaves zero merchandise. A£23.12 credit exceeds that subtotal by one penny and is rejected. These calculations do not create entitlement to a discount or verify a promotional code.
Charges survive full credit
With a full merchandise credit, hypothetical entered delivery£4.99 and additional tax£1.25 still total£6.24. These are test inputs, not observed merchant charges. If a charge is blank or invalid, the site withholds a full total. It does not assume free delivery or add VAT again to a tax-inclusive ticket.
Bounded input handling
Prices use integer pence with at most two decimal places; quantities are whole selected packages. Negative values, scientific notation, extra precision and inputs above one million are refused. £0.10 multiplied by three is£0.30, and£47.99 multiplied by two is£95.98 without floating-point subtotal drift.
Use the genuine ticket
Replace the default with the actual selected price if the checkout differs. Keep a consistent tax basis and confirmed charges. The tool does not predict reorder frequency, calculate an infant dose, collect health data or transmit purchasing information to a merchant.
Sources & scope
Checked November 5, 2026. Manufacturer and retailer references support the specific statements. Dated displayed prices are not final checkout quotes, performance rankings or performance testing. This shopping reference does not replace the exact product label or retailer instructions. Current received labels and independent paediatric/clinical/material/content/commerce review remain pending.