23 or 29
The only prime between 8 and 12 is 11.To find out if a number is prime, just try dividing it by all prime numbers between 2 and that number (including 2). The easiest method to do this is to write all numbers from 2 to your number down. Then cross out all numbers divisible by 2. Now cross out all numbers divisible by the next lowest number that is not crossed out (which is 3). Repeat this last step (the next number should be 5, then 7, then 11) until you reach your number, or you cross it out. If you have crossed it out, it is not a prime number, and if it has not been crossed out it is a prime number.
100.00001
9
I don't have that one in front of me. Perhaps you could write down the problem for me.
11 is already prime.
The breaking down of a composite number into its prime number factors.
13 is already prime. Just write it down.
The is no last prime number - unless you are counting down, in which case, it is 2.
Write down all the numbers between 4 and 40. Cross out the prime numbers and count them. You need to do your own math and getting the answer here won't help you pass your state standards.
factoring
A number which is divisible by only itself and 1 is called a prime number. It means a prime number has only two factors.Let us say n is a prime number then its factors are 1 and n.So for any prime number we can easily write its factors because it has only two factors: 1 and the number itself.Similarly we can write the factors of prime numbers from 1 to 100.2: 1 and 23: 1 and 35: 1 and 57: 1 and 711: 1 and 11 & so on.From the definition of prime number it is clear that writing down the factors of a prime number is not a difficult task because we don't need to do any calculation.But for the prime numbers from 1 to 100 writing the factors is a tedious task as it involves nothing but writing 1 and the number itself.For the list of prime numbers visit the related questions.