These are rectangles that show all the factor pairs for the numbers 1-30. All three classes worked on a set for their classes. Here's what we discovered:
Prime numbers only have two rectangles, because they only have 1 and the number as factors.
Some numbers make square rectangles, but only special numbers like 4, 9, 16, and 25. That's because they are created when you multiply a number by itself (like 2 x 2 = 4). These numbers have an odd number of rectangles that can be made. These are called Square numbers (one of their factor pairs creates a square).
Most numbers have an even number of rectangles (like 21 has 1 x 21, 21 x 1, 3 x 7, and 7 x 3). Numbers that have more than themselves and one as factors are known as Composite numbers.
We have also been practicing applying the rules of divisibility.
Prime numbers only have two rectangles, because they only have 1 and the number as factors.
Some numbers make square rectangles, but only special numbers like 4, 9, 16, and 25. That's because they are created when you multiply a number by itself (like 2 x 2 = 4). These numbers have an odd number of rectangles that can be made. These are called Square numbers (one of their factor pairs creates a square).
Most numbers have an even number of rectangles (like 21 has 1 x 21, 21 x 1, 3 x 7, and 7 x 3). Numbers that have more than themselves and one as factors are known as Composite numbers.
We have also been practicing applying the rules of divisibility.