what number is a prime

4
13
26
15

https://www.mathsisfun.com/prime_numbers.html

he did well but needs to do quicker I can tell he tried his best but he needs more help on questions 3,11,12,15,18,21,22 and 29 number 1 he did right but I can tell he struggled a lot he score was 7/40

To determine whether a number is prime, you need to check if it is divisible by any number other than 1 and itself. Let's go through each number and check if it meets this criterion:

1. 4: To check if 4 is prime, we need to find if it is divisible by any number other than 1 and itself. In this case, 4 is divisible by 2, so it is not prime.

2. 13: For 13, we check if it is divisible by any number between 2 and its square root (which is around 3.6). Since it is not divisible by any such number, we can conclude that 13 is prime.

3. 26: Using the same process, we check if 26 is divisible by any number between 2 and its square root (which is around 5.1). In this case, 26 can be divided by 2, 13, and 26 itself, so it is not prime.

4. 15: Once again, we check if 15 is divisible by any number between 2 and its square root (which is around 3.9). As 15 can be divided by 3 and 5, we can determine that it is not prime.

So, out of the given numbers, 13 is the only prime number since it is not divisible by any number other than 1 and itself.