What I do is start with 2's and 5's because they're easiest, since every even number is evenly divisible by 2 and every whole number ending in 5 or 0 is evenly divisible by 5. Then I start from 3 going through the prime numbers, dividing the remaining part of the number by each Prime number on a calculator to see if the quotient is a whole number. I continue whittling away at the number in that way with each prime number in order until the quotient I get is less than the prime number divisor I tried; at that point I know that what's left over must be a prime number.
One strategy is estimating the factors the other i don't know
To know that a number is prime you need to know that it has no factors other than 1 and the number itself.To know that a number is composite you only need to know one factor other than the number itself or 1.
How to know that you found all the factors for example my teacher taught me that when u reach a double diget number that is all the factors. ( 6x6)-~ double diget number
You don't.If you know just one factor, other than 1 and the number itself, you will know that the number is composite.A prime has only two factors: 1 and itself. So all the factors is no big deal.
No, an odd number can have any number of factors. There is no limit but you do know that the number 2 is not one of those factors.
There will be an odd number of different factors.
When all the factors are prime.
It has more than two factors.
Yes, you do. And know them well, or else you'll get it wrong! Well, not exactly. To determine that a number is prime you need to know that the number has exactly two factors, which means that there are no other factors. You know that a number is composite by finding just one factor that is neither one nor the number itself.
But you do know the factors of prime numbers. Every prime number has two factors: one and the number itself.
You know that 7 is a prime number because it only has two factors.
All of the factors are prime.