Just like every other kid on earth, my brother and I would always try to find ways to peak at (or into) our Christmas presents before the big day. One year, my dad wised up and instead of putting names on the tags, he numbered them and had some memorized formula to resolve it to its recipient. Well Dad, thanks for the idea. I’ve been doing it for years and it works great. But this year, I decided to mix it up a little and make it into a “challenge” for my own boys. I never did figure out my dad’s formulas, but I suspect it didn’t differ to much from those that I’ve used over the years. My formulas are usually very simple, and always resolve to either an even or odd number (the kids have figured this out). Each year I change it up, so they cannot figure …keep reading …