why is 4 or 6 not a prime number?

A prime number can be divided only by itself and 1.

4 and 6 can be divided by 2 so are not prime.

Because 4 = 2 x 2, and 6 = 2 x 3
Prime numbers can only be decomposed into 1 x <the number>.

A prime number is one that cannot be divided by anything except itself or 1. you can divide 4 by 2 for example, so it's not a prime number.

pime number is d number only can divide by itself and 1..
4 can be divide by 1,2,4
6 can be divide by 1,2,3.6
that mean 4 and 6 is not prime number.. but 1 are not prime number..

A prime number is only divisible by 1 and itself (2,3,5,7,11,13...)
4 is also divisable by 2.
6 is divided by 2 and 3.
all square numbers are not prime.
4 is a square number

I'm with morningfoxnorth on this one.

4 = 2 * 2 is the product of two whole numbers both greater than one. So is 6 = 2 * 3.

Prime numbers are the whole numbers, greater than one, which CANNOT be represented as a product of two other whole numbers both greater than one. Therefore by representing 4 and 6 as products like that, we show that they are not prime numbers.

All answers above are correct. These are the first fifteen prime numbers:

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47

As you can see, none are divisible by any number other than themselves and 1.

because a prime number is a number that can only be divided by itself and 1
e.g 19
but 4 and 6 can be divided by other numbers

Because they are divisible by another number eg 2.
The number 7 however is a prime number because you cannot divide it by another whole number (apart from 1 or 7)

A prime number is divisible by only 1 and itself.

4 is divisible by 1, 2, 4

6 is divisible by 1, 2, 3, 6