A prime number has exactly two factors, itself and one. The first ten prime numbers are \({2}\), \({3}\), \({5}\), \({7}\), \({11}\), \({13}\), \({17}\), \({19 ...

Another way to think of prime numbers is that they are only ever found as answers in their own times tables. 11 is a prime number because the only factors of 11 are 1 and 11 (\(1 \times 11 = 11\)).