For the solution, click "Read More" below.
Wednesday, November 24, 2021
The Stripey Triangle Problem
Tuesday, November 9, 2021
The Consecutive Number Problem
Ginger writes down a sequence of numbers. Each is a positive whole number from 1 to 11, and she uses each number only once. Henrietta looks at the sequence and notices that for every pair of numbers next to each other in the sequence, one is divisible by the other. What is the maximum number of numbers that Ginger wrote down?
For the solution, click "Read More" below.
Sunday, November 7, 2021
The Rolling Cube Problem
For the solution, click "Read More" below.
Monday, October 25, 2021
The Birthday Party Problem
Betty’s friends threw her a birthday party. Everyone (including Betty) met exactly 3 new people at the party.
When Betty told her mom about the party later, her mom said, “That sounds like fun! How many people were there at the party?”
“I think there were 14, or maybe 15, including me,” answered Betty.
Question: If Betty was right that there were either 14 or 15 people at the party, then which number is correct?
For the solution, click "Read More" below.
Saturday, October 23, 2021
The Isosceles Triangle Problem
The lines below are parallel.
For the solution, click "Read More" below.
Friday, September 24, 2021
Four fours!
Place operation symbols between the ones to make the equations true. (Use the four operations and parentheses.)
1 1 1 1 = 0
1 1 1 1 = 1
1 1 1 1 = 2
1 1 1 1 = 3
1 1 1 1 = 4
Work out:
4 4 4 4 = 0
4 4 4 4 = 1
4 4 4 4 = 2
4 4 4 4 = 3
4 4 4 4 = 4
4 4 4 4 = 5
4 4 4 4 = 6
4 4 4 4 = 7
4 4 4 4 = 8
4 4 4 4 = 9
4 4 4 4 = 10
For the solution, click "Read More" below.
Thursday, March 25, 2021
Toothpick Puzzle!
This is a repost of a problem from several years ago. This time I am including an interactive document that you can use to move your toothpicks around and create your figures. First, make sure you are signed in with a Google/gmail account  otherwise you will be able to see the document but can't make your own copy. Open the document and then under the "file" menu, click "make a copy" to make your own copy: Toothpick Perimeter document
Here's the problem:
Notice that you can make figures with toothpicks. We can think of each toothpick as a unit of length. Below I made a figure with a perimeter of 12 and an area of 9:
For the solution, click "Read More" below.
Sunday, February 28, 2021
PLAYFUL MATH BLOG CARNIVAL #163
BLOG CARNIVAL #163....LET'S GO! Fun fact: The number 163 is prime, which we can prove simply by showing that it is not divisible by 2, 3...

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To a topologist, two shapes are "the same" if one can be stretched, twisted, and distorted into the other shape without b...