Today is student choice day, where I look through the Edmodo submissions from my students and choose a short and snappy opener. Chris B. submits this number “magic” as a video worth sharing with the class:
What’s going on here? Is it just plain coincidence? Dumb luck? The devil’s work? 37 is certainly not a number we encounter too often in our daily math life.
A student in my afternoon class quickly picked up on the mystery:
37 times 3 is 111, and they all have 111 in them
Good enough. Converting a division example from the video into multiplication helps verify the claim”
777 = 37 * 21
111 * 7 = 37 * 3 * 7
It’s a quiz day, but I leave the class with the following challenge:
Develop a similar pattern for a longer string of identical numbers
They are pretty easy to find, such as the one below for five-digit strings. And Chris provided a low-stress math challenge to get us into math thinking mode before our quiz.
mathcoachblog 