A prime number is a whole number greater than 1 that has no divisors other than 1 and itself. This means that a prime number can only be divided evenly by 1 and itself. Let's explore the prime numbers up to 20 together!
First, let's start with the number 2. It is the first and only even prime number since all other even numbers have 2 as a divisor. This means that any other even number will always have at least one more divisor besides 1 and itself, making them composite numbers.
Next, we have the number 3. It is the first odd prime number. When we divide 3 by 1, it gives us a whole number, and when we divide it by 3, it also gives us a whole number. There are no other whole numbers that can divide 3 evenly without leaving a remainder, so 3 is a prime number.
Moving on to the number 5. Like 3, when we divide 5 by 1, it gives us a whole number, and when we divide it by 5, it also gives us a whole number. There are no other whole numbers that can divide 5 evenly, so 5 is also a prime number.
Continuing this process, we find that 7, 11, 13, 17, and 19 are the remaining prime numbers up to 20. These numbers cannot be divided evenly by any other whole number except 1 and themselves, making them prime.