1 is not taken among the factors.why?

Question

for my mathematics subject 'Factors and Multiples'

Answer 1

1 *is* a factor of a number, just like the number itself is.

For example, the factors of 12 are:
1, 2, 3, 4, 6, 12 and the negative factors of -1, -2, -3, -4, -6, -12.

However if you are looking for *prime* factors, 1 is not a prime number, so it is not included. In the example above, the prime factors are 2 x 2 x 3.

Answer 2

Because it is trivial. Also 1^n=1 for any n, so the question how many times it is contained as a prime factor does not have a unique answer.

Answer 3

1 is not a factor because it is in every number. It is referred to prime if the only factors are 1 and itself.