Why is one not a prime or a composite number?

Answer 1

1 is evenly divisible only by 1 and itself (also 1). In that respect it is like a prime. However, if 1 were a prime then the Fundamental Theorem of Arithmetic - the Unique Prime Factorisation Theorem would fail - and with it much of arithmetic would become invalid.

Answer 2

1 is evenly divisible only by 1 and itself (also 1). In that respect it is like a prime. However, if 1 were a prime then the fundamental theorem of arithmetic - the unique prime factorisation theorem would fail - and with it much of arithmetic would become invalid.

Answer 3

A Prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 have a different name.

Answer 4

It doesn't have enough factors to qualify.

Answer 5

It doesn't have enough factors to qualify.

Answer 6

1 only has 1 factor. A prime number has to have 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 have a different name.

Answer 7

Wrong number of factors.