A man in Hull

The mistake

The free-delivery threshold is stored in pence (5000) while the basket subtotal is read in pounds, and the shortfall is rendered straight into a currency string with a pound sign. Subtracting the £2.00 basket from 5000 gives 4800, which the bar prints as "£4,800 more" instead of the correct £48. Because the unit mismatch is in the shared formatting path, every basket in the shop shows a figure inflated by a factor of a hundred.