23 is a prime number. 23 = 1 x 23. Its only factors are 1 and 23. Prime factorization: none.
How do we know that 23 is a prime number? The square root of 23 is an irrational number approximately equal to 4.796. If 23 were not a prime number, then it would be divisible by at least one prime number less than or equal to 4.796. Since 23 is not divisible by 2 or 3, it is a prime number.
23 is never a clue in the FIND THE FACTORS puzzles.
I want to thank beyondtraditionalmath.wordpress.com for originally publishing this post. It can really help anyone visualize what multiplication means. Still I hope it doesn’t completely replace the traditional multiplication table because that old, familiar table is the basis for my Find the Factor puzzles.
Have you even seen this yet?! Click on the image to go straight to the PDF of this amazing multiplication table by David Millar of thegriddle.net. It is free to educators to print and use in the classroom. Even better if you go to the educator section, there is a black and white version that is both with and without numbers.
My mind is churning with the possibilities for using this in the classroom! I think it is the best multiplication table I’ve certainly ever seen. Talk about helping students conceptually understand multiplication, connect it to arrays as well as the concept of area.