Countdown To Christmas - With Math Problems??

Submitted by Brooke Istas on Mon, 12/12/2016 - 20:44
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Hello Community Members,

I am going to start a discussion with a countdown to Christmas with Math Problems!  The count down will begin on Dec. 15, and I will be posting a new math problem each day!  If you have an interesting math problem - please post it below, too, the more the merrier! I look forward to posting as we count down to Christmas!

Best,
Brooke Istas
Moderator, Math and Numeracy COP

Comments

Hi Brooke,

Here's a problem our math teachers' circle explored recently:

Dana’s Rectangle

Using a sheet of grid paper, Dana marked a rectangle and drew a picture inside the rectangle. Then she surrounded the rectangle by a one-square-wide border consisting of grid squares. It turned out that the area of the border is exactly the same as the area of the inside rectangle.

What size is the rectangle? List all possible sizes and prove that other sizes won’t work.

Dana's Rectangle (handout)

Best,
Eric