Not sure where to start? These are the lessons and games we recommend most to students, parents and teachers on Basic-mathematics.com. Each lesson explains the topic in plain language, walks you through worked examples step by step, and ends with practice so you can check your understanding. Pick one below, or use the menu to find lessons on fractions, algebra, geometry, statistics and more.
The prime number calculator will check if a number is prime or not and in each case will offer a step-by-step explanation. You also ave the opportunity to see a list of prime numbers up to 1 million (1000000).
Recall that a number is prime if it can only be divided by 1 and itself.
Why is 9 not prime?
9 has factors other than 1 and itself. Here's a detailed explanation:
The smallest factor (other than 1) is 3. You can divide 9 by 3 to get 3.
Remember: Any number that's not prime is called a composite number (except for 1, which is neither prime nor composite).
7 is prime because it can only be divided by 1 and 7
Sometimes, it is tricky to see if a number is prime or not. Try putting 93 in the calculator and you will see that 93 is not prime because it can be divided by 3 and 31.
However, 93 looks prime if you do not take time to think about.
Use the calculator below to practice until you have no problem recognizing what a prime number is.