Welcome to the third of our Difficult Eleven Plus maths quizzes on Properties of Numbers. Do you know about prime numbers, factors, multiples and square numbers? Hopefully, you will have played our previous quizzes and be quite familiar with them. This quiz gives you more opportunity to practise with them. Many people mistakenly believe that 1 is a prime number because prime numbers are divisible by themselves and by 1. This does apply to the number 1, but it is not a prime number. Why? Well, prime numbers are divisible by two numbers: 1 and themselves. 1 is not a prime number because it is only divisible by one number – the number 1. The more often you play these quizzes, the better you will become at maths. Even when you have mastered a topic, it’s a good idea to come back and play the quizzes again. We can all get a little rusty over time!