A Prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 are neither prime, nor composite.
It is a composite number because it has at least one positive factor other than one or itself.
1 + 5 + 6 + 3 = 15 15 is a multiple of 3. 15603 is a multiple of 3. That makes it composite.
33772 ends with a 2. Any positive integer ending with 0, 2, 4, 6 or 8 - other than 2 itself - is divisible by 2 and so is a composite number. The fact that it has one proper factor is sufficient to establish that it is not a prime. You do not even need to know its factors.
There is no set formula to make a prime number into a composite but usually adding 1 will work. A prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1, 2, and 0.
Composite Work: A prime number is only divisible by itself and one. 74 is divisible by 2 and 37 Not prime. As soon as you see that '4' at the end, you know it's an even number. No even number (except '2') can be a prime, because in addition to itself and '1', it also has '2' for a factor.
You could try dividing by composite numbers but the number that you are testing is divisible by a composite number, then it will be divisible by a prime factor of that composite number and that prime factor will be smaller. It is always easier to work with smaller numbers.
where is it
There is no work. The only prime number ending in 5 is 5.
13 is already prime. Just write it down.
5 x 13 = 65 To show work, divide 65 by 5.
343 49,7 7,7,7