April showers have ushered in May flowers — and a second Math Calendar, with daily puzzles from my homeschool co-op students. Get your copy here:
Puzzle: Factoring Trinomials
My high school class ended the year with a review of multiplying and factoring simple polynomials. We played this matching game, and then I gave them a puzzle worksheet. I liked this idea, but I didn’t like the decoded answer. In my opinion, puzzles should give the student a “reward” for solving them — maybe a joke or riddle or something — but that answer seemed almost like nagging.
So I changed things around to make my own version:
How Much is a Trillion?
[Photo by reubenaingber.]
If you collected stacks of $100 bills, could you fit a trillion dollars into your bedroom?
In your house?
In a warehouse?
If you spent a dollar a second, how long would it take to spend a trillion dollars?
[HT: Justin Taylor at Between Two Worlds.]
2009 Mathematics Game
[Photo by Amanda M Hatfield.]
Have you made a resolution to exercise your mental muscles this year? Then please join us for the 2009 Mathematics Game. Here are the rules:
Use the digits in the year 2009 and the operations +, -, x, ÷, sqrt (square root), ^ (raise to a power), and ! (factorial) — along with parentheses, brackets, or other grouping symbols — to write expressions for the counting numbers 1 through 100.
- All four digits must be used in each expression.
- Only the digits 2, 0, 0, 9 may be used.
- The decimal point may be used, as in .9, .02, etc.
- Multi-digit numbers such as 29 or 902 may be used, but preference is given to solutions that avoid them.
By definition: 
[See Dr. Math’s Why does 0 factorial equal 1?]
For this game we will accept: 
[See the Dr. Math FAQ 0 to the 0 power.]
Christmas Puzzle: The Grinch Bug
[Photo by theogeo.]
Christmas afternoon is a slow time at our house. How shall we while away the hours until the turkey is done? With math, of course!
Check out this puzzle from Blinkdagger.
MathCounts — Ready or Not, Here It Comes
[Feature photo above “You’re a mean one, Mr. Grinch” from CheezBurger.com.]
Okay, kids, I know you’re on break, but Mr. Grinch would tell you that’s no excuse to laze around playing games and eating cookies. There is only a month until our school MathCounts competition, which doesn’t give you much time to prepare. I’ve collected several resources to build up your mental muscle-power before the test…
Math Club: Counting 101
[Fature photo above by ThunderChild tm.]
The last couple of weeks, in Math Club, we’ve been learning to count. My new set of MathCounts students have never heard of combinatorics, so we started at the very beginning:
- Counting and Probability I by Keone Hon
- Counting and Probability by Jason Batterson
Substitute Teacher Experiments with Combinatorics
Photo by peigianlong.
Here is a puzzle from Just a Substitute Teacher:
Lesson plan entry: “Hand out worksheet packets and have students staple before starting. They know what to do.”
Sounds simple enough! Four numbered sheets, eight total pages, printed front and back. What could go wrong?
Do you know how many possible combinations four pieces of paper can be arranged for stapling?
Continue reading Substitute Teacher Experiments with Combinatorics
Answers to Leon’s Figurate Number Puzzles
Remember the Math Adventurer’s Rule: Figure it out for yourself! Whenever I give a problem in an Alexandria Jones story, I will try to post the answer soon afterward. But don’t peek! If I tell you the answer, you miss out on the fun of solving the puzzle. So if you haven’t worked these problems yet, go back to the original post. Figure them out for yourself — and then check the answers just to prove that you got them right.
Puzzle: Figuring Out Figurate Numbers
Photo by frumbert.
Alexandria Jones‘s parents decided that the family needed to relax after the excitement of tracking Simon Skulk, so they spent the next day at a beach on the Mediterranean coast. Leon collected pebbles and tried to build up figurate numbers — numbers that make a figure, or shape — the way Dr. Theano had shown them.
Denise Gaskins' Let's Play Math 