🧃 Vending Machine
A vending machine for first graders to practise breaking an amount into notes: every drink shows its price, tapping a note in the tray sends it flying into the slot, the little screen adds up note by note, and when the amount is exactly right the drink drops into the pickup bay. Put in too much and the machine simply spits the last note back out, then shows how to split the amount, for example 12,000 = 10,000 + 2,000. Three levels from 10 to 50 thousand dong; higher levels use odd prices so several notes must be combined.
Tap a note in the tray to send it into the slot; the little screen on the machine adds up note by note. Insert exactly the price and the drink drops into the pickup bay; insert too much and the machine spits the last note back out while a speech bubble shows how to split the amount. The ↺ button returns every inserted note to the tray so you can start the turn over, and tapping the highlighted drink reads the question again. Five correct buys in a row earn a star.