Use integer pence
The ledger parses GBP amounts with at most two decimal places into integer pence. The three observed single-roll tickets total 1647p, displayed £16.47 ex VAT. Multiplication is performed on those integers, so £0.10 times three remains £0.30 and £47.99 times two remains £95.98.
Full credit is a valid boundary
A confirmed merchandise-only credit of £16.47 reduces that merchandise subtotal to zero. £16.48 is one penny too much and is rejected. A zero merchandise balance does not erase delivery, additional tax or other confirmed charges. No coupon eligibility or actual credit entitlement is inferred.
Keep unknown charges unknown
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 fees. If any charge is blank or invalid, the site withholds a full total rather than assuming zero or calculating a tax rate.
Input limits are part of the answer
Negative amounts, more than two decimal places, scientific notation, fractional offer counts and values above one million are rejected. The calculator submits no order or payment details. Use a consistent tax basis and the genuine current basket before making a purchasing decision.
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 medical/material-claims/content/commerce review remain pending.
SPORTTAPE Pink5cm×5m Single Roll45473057669436 ↗
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