Why do 0 and 1 neither composites nor primes? Is this true?

OK. I have an exam lately in my computer lesson – Basic Switching Theory.

One of the question is that:
Make a logic diagram outputs HIGH when the input is a prime number.

After the exam, some of my classmates told me that 0 and 1 are neither composites nor primes. I asked them why, but they didn’t answer me. They only said that it is JUST they’re not composites nor primes.

I am really confused. And because of that i am now unsure of my answer. HELP.

The number 1 is not prime because, by definition, primes are greater than 1. If 1 was prime, then the Fundamental Theorem of Arithmetic wouldn’t hold, and that would be a Bad Thing.

The number 1 is not composite by definition.

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One Response to Why do 0 and 1 neither composites nor primes? Is this true?

  1. jgoulden says:

    The number 1 is not prime because, by definition, primes are greater than 1. If 1 was prime, then the Fundamental Theorem of Arithmetic wouldn’t hold, and that would be a Bad Thing.

    The number 1 is not composite by definition.
    References :
    http://primes.utm.edu/notes/faq/one.html