I'm getting worried with my basic math skills.

TWICE in 4 days, I've not been able to give the right amount of cash for small purchases.

Thursday : Ice cream sandwich - costs 1.25, I gave the guy 6 quarters; he gave me back one quarter.

Sunday : Ice tea - costs 1.49, I gave the guy 3 dollars; he gave me back one dollar.

Argh! What's wrong with me?