Money not enough?

My son called me earlier from school.

son: "Mummy, I don't have enough money to buy food."
mummy: "But how is that possible? I thought u said u have some coins with u?"

son: "Got, but only 4 coins. Not gold coins. Not enough."
mummy: "Go find jie jie for money. Tell me exactly how much you have?"

son: "Jie jie not here. Can't find her. My coins all 20cents one."
mummy: "That makes it 80cents in all. Enough lah, my dear. Go buy something."

son: "ok.."

Mmm., looks like I have to train him how to count his coins tonight. Strangely, jie jie does'nt seem to have this problem when in P1.