How it works
In the made-up town of this story, Pia put a forty-coin bike on a card, so forty coins were owed. The bank adds one extra coin for every full ten owed, so the extra is four.
The statement said 44 and a minimum payment of 5. The minimum is the least the bank accepts this month. Four of the five coins paid the extra, so only one cut the forty.
Paying only the minimum, the balance creeps down one coin a month, and forty coins take forty months. Pia paid 104 coins for a bike that cost 40.
A minimum is a gate, not a finish line. Paying more each month shortens the road.