She spots wrong change at our shop counter. A maths class this young, or leave it alone?

On the odd evening she comes to the shop with me, our daughter sits by the counter and watches the change tray. Yesterday she told a customer he'd paid ₹10 extra before anyone else noticed 😊 Amma is now convinced she needs a proper maths class 'before the spark goes'. Her school is IB and very play-based, no sums on paper yet, and her teacher didn't seem bothered when I asked. Is there any point in a structured class at this age, or does it turn a fun thing into homework? If anyone in Vashi knows a class that isn't just drilling, I'd like to at least look.