A prime number is a number with factors of one and itself.

Let's try to find the factors.

It may not be easy to see as a composite number, but if you know the divisibility rule for which is double the last digit and subtract from the rest , you will see is not prime.

A prime number is a number with factors of one and itself.

Let's try to find the factors.

It may not be easy to see as a composite number, but if you know the divisibility rule for which is double the last digit and subtract from the rest , you will see is not prime.

The first seven primes are 2, 3, 5, 7, 11, 13, and 17. Don't forget about 2, the smallest prime number, and also the only even prime! Adding these seven numbers gives a sum of 58, and 58/2 = 29.

The first seven primes are 2, 3, 5, 7, 11, 13, and 17. Don't forget about 2, the smallest prime number, and also the only even prime! Adding these seven numbers gives a sum of 58, and 58/2 = 29.

A prime number is a number with factors of one and itself.

Let's try to find the factors.

It may not be easy to see as a composite number, but if you know the divisibility rule for which is double the last digit and subtract from the rest, you will see is not prime. The divisibility rule for is add the outside digits and if the sum matches the sum then it is divisible . The divisibility rule for is if the digits have a sum divisible by , then it is . All even numbers are composite numbers with the exception of . So with these analyses, answer is .

A prime number is a number with factors of one and itself.

Let's try to find the factors.

It may not be easy to see as a composite number, but if you know the divisibility rule for which is double the last digit and subtract from the rest, you will see is not prime. The divisibility rule for is add the outside digits and if the sum matches the sum then it is divisible . The divisibility rule for is if the digits have a sum divisible by , then it is . All even numbers are composite numbers with the exception of . So with these analyses, answer is .

Since all the numbers are odd and don't end with a , let's check the basic divisbility rule. The divisibility rule for is if the digits have a sum divisible by , then it is.

Based on this analysis, only is divisible by and therefore not prime and is our answer.

Since all the numbers are odd and don't end with a , let's check the basic divisbility rule. The divisibility rule for is if the digits have a sum divisible by , then it is.

Based on this analysis, only is divisible by and therefore not prime and is our answer.

This will require us to know the divisibility rule of . The reason for this choice is that some of the numbers are palindromes like so we eliminate . For the three digit numbers, the divisibility rule for is add the outside digits and if the sum matches the sum then it is divisible. Let's see.

Based on this test, is not divisible by and is our answer.

This will require us to know the divisibility rule of . The reason for this choice is that some of the numbers are palindromes like so we eliminate . For the three digit numbers, the divisibility rule for is add the outside digits and if the sum matches the sum then it is divisible. Let's see.

Based on this test, is not divisible by and is our answer.