I'm off to Florida in a few hours to attend a Coins In The Classroom conference put on by the American Numismatic Association. Anyone can use coins to teach history, geography, even language, but algebra and trigonometry? I'm curious :-) Even I have found only two direct applications of Algebra 1 skills to coins, and I've put a lot of thought into this over the years.
Anyone want to know what they are? OK, I'll tell you.
1. Subtracting negative numbers (How old is this coin minted circa 240 BC?)
2. 2-step algebraic equation (What year was this Saudi coin minted, given that they use the 356-day-long year of the AH calendar instead of the AD calendar?)
I'm open to other ideas, and if I learn any at this conference I'll be sure to pass them on.