You know, sometimes numbers can feel a bit like people – some are quite solitary, while others are happy to mingle and share. When we talk about prime numbers, we're usually thinking of those independent types. A prime number, at its heart, is a positive whole number greater than 1 that has only two divisors: 1 and itself. Think of 7, for instance. You can only divide it evenly by 1 and 7. It's a bit of a loner in the number world, in the best possible way.
Now, the flip side of this is what we call a composite number. These are the social butterflies. A composite number is any positive whole number greater than 1 that can be divided evenly by numbers other than just 1 and itself. It has more than two factors. The reference material I looked at puts it quite clearly: a composite number is a positive number that can be divided by positive numbers other than 1 and itself. It's essentially any number that isn't prime.
So, where does 90 fit into all this? Let's take a look. Can we divide 90 by anything other than 1 and 90? Absolutely! We can divide it by 2, and we get 45. We can divide it by 3, and we get 30. We can divide it by 5, and we get 18. We can even divide it by 6, 9, 10, 15, 18, 30, and 45. That's a whole lot of divisors, isn't it?
Because 90 has so many divisors besides 1 and itself, it doesn't fit the definition of a prime number. Instead, it fits perfectly into the category of a composite number. It's one of those numbers that's happy to be broken down into smaller parts, showing off its many factors. It's not a solitary prime; it's a friendly composite.
