Preparing for the new school year, which begins Wednesday, I made myself a deck of cards for a math game that I intend to play with my students. My brother-in-law Justin told me about this game.
You have 48 cards, two each of the positive integers 1-24. I made my deck from some old card-catalogue cards that I pilfered from an enormous boxful in the library. On the back they say things like "FIC Trollope, Anthony." I'm pretty sure that's a fine way to find cards, but you might want to check with your local librarians. Make sure that your numbers are unambiguous or you will wrestle with temptation to interpret them favorably and the lack of integrity will rob you of the joy of solution.
Shuffle the deck and draw 5 cards. Now arrange the first four in such a way with appropriate math symbols so that you have an expression which equals the value of the fifth card.
I drew five cards to come up with an example, wondering if I would be able to figure out an answer or if I would have to lie so that you think my game is cool. I did find an answer, but you might think that I am lying anyway.
I drew: 6, 10, 4, 21, and 16.
I stared blankly at the cards for a minute... [this step is critical]
21-10/(6-4) = 16.
Justin has told me that they have yet to find a group of cards with no solution.