A Multiplication Based Logic Puzzle

Posts tagged ‘Education’

65 and Factors, products, primes and composites

65 is a composite number. 65 = 1 x 65 or 5 x 13. Factors of 65: 1, 5, 13, 65. Prime factorization: 65 = 5 x 13.

This post is an excellent example of how the FIND THE FACTORS puzzles can be included in mathematics instruction. I really liked the students’ description of what they did in class with the puzzles.

There are two easy ways to copy the puzzles for use in the classroom. If you click on any of the excel files that contain 6 puzzles, you will find all 6 puzzles available in two different print sizes: 6 small ones per page or 2 large ones per page. You can also copy any jpg picture that is on the blog, paste it onto a word document, and then make the picture as big as you want on the document. The excel file will probably give you a cleaner copy though.

If the only way you can access the puzzle is on a device that isn’t connected to a printer, you will probably have to hand draw or reproduce a copy of the puzzle as 6è Primària did in order to use it. That requires real commitment!

Please include the puzzle title and copyright information when you make copies for the classroom or any other non-commercial use.

7 and Spaghetti and Meatballs for All!

7 is a prime number. 7 = 1 x 7. Its only factors are 1 and 7. Prime factorization: none.

How do we know that 7 is a prime number? The square root of 7 is an irrational number approximately equal to 2.65. If 7 were not a prime number, then it would be divisible by at least one prime number less than or equal to 2.65. Since 7 is not divisible by 2, it is a prime number.

When 7 is a clue in the FIND THE FACTORS puzzles, one factor will be 7 and the other will be 1.

Spaghetti and Meatballs for All! by Marilyn Burns is a delightful story, the kind that children enjoy hearing over and over again.


I work at a Leader in Me school, where we promote the Seven Habits. I used this book when I taught about habit 4, think win-win. When we think win-win, we do not allow someone to “step on us’ to give them a win. Mrs. Comfort’s relatives stepped on her over and over again, and they didn’t even realize it. Finally she cried, “I give up!” and planted herself on a chair. She definitely felt like she was losing. The class listened to the story intently trying to identify places where the Seven Habits were used or could have been used. We had a great discussion afterwards. Also since the book did not use the words, “area” or “perimeter” at all, the class hardly realized that the story was also about those concepts. When we followed the suggestions at the back of the book, the class was able to learn about perimeter and area as we had a great discussion about those topics as well. 


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