Learning to count change

Customers bring their shopping and pay with a note, for example Rp3,000 of goods paid with Rp5,000. The child must give the right change before the customer’s patience bar runs out. Too slow or wrong change and the customer complains, the shop loses reputation, and the correct working is shown (5,000 − 3,000 = 2,000). There are 5 levels: level 1 has one item with round numbers and answer choices, level 2 two items, level 3 builds the change from Rupiah coins and notes, level 4 adds hundreds and customers paying with coins, and level 5 asks the child to add up the total first. Prices shift every trading day, so the questions are always different. A day has 8 customers and ends with a report: served, complaints, tips, and accuracy.