Keep the ordinary selected base
At the observed ordinary prices,one 48-pack Ultra Dry,one 42-pack Easy Fit and one 84-pack Pampers give£20.20 merchandise. The ledger validates GBP strings and converts them to integer pence before multiplying whole-pack counts. It does not derive a discount from a rounded shelf unit rate.
Allow exact full merchandise credit
A confirmed merchandise-only credit of£20.20 leaves exactly£0 merchandise. A£20.21 credit exceeds this base and is rejected. That is an arithmetic boundary,not a live voucher,gift-card validation or a promise that a retailer accepts your entered promotion.
Retain confirmed separate charges
Shipping,actual additional tax and other charges remain separate. In a test,£4.99 shipping plus£1.25 additional charge still leaves£6.24 payable after full merchandise credit. These are test figures,not observed Tesco or B&M fees. Blank charges keep the full total unresolved rather than being treated as zero.
Reject unclear inputs
Negative amounts,more than two decimal places,exponent notation,fractional pack counts and inputs above the stated limit are rejected. Do not repeat tax already included in an actual quote. No order,payment detail,child identity or medical information is transmitted by these tools.
Apply it to the selected purchase
A second boundary test uses£47.99 times two equals£95.98,and£0.10 times three equals£0.30. Those are calculation tests,not observed nappy prices or a reason to change the selected-pack quotes.
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/material/content/commerce review remain pending.
Tesco UK Fred & Flo48 Size4 product304794654 ↗