Why 1 is not a prime number
This post investigates the mysterious question, why 1 is not a prime number.
Let's quickly define what a prime number is (I have talked about primes before in an my older post called "Prime Numbers", which will tell you all about what a prime number is, and a cool video of Adam Spencer talking about "monster primes").
Alot of people think that number 1 is a prime number because the basic prime number rule is that the number can only be divided by itself and 1 (there are no other possible factors). In this case, 1 divided by itself = 1, but that is actually the exact reason it is not prime. In fact, even my sister's maths teacher was telling her class recently that 1 should be considered prime.
So why is 1 not prime? Because, as explained by my favourite mathematician Adam Spencer on the 26 June 2014 Sleek Geeks podcast The Number One, Big Data and Twittertime (you can find it on iTunes - just search up "Sleek Geeks" in Podcasts) no prime number multiplied by another prime number can be prime. Sounds a bit confusing, but if you think about 3, that is prime because it is 1x3, but that means one of factors cannot be prime. So we know 3 is prime, which means 1 cannot be. Also, 1x1 would be two prime numbers being multiplied, which does not fit the rule for "primacy". So that is why 1 is not a prime number.
For a bit more information on why 1 is not prime, check out this page, which gives more detail.
Let's quickly define what a prime number is (I have talked about primes before in an my older post called "Prime Numbers", which will tell you all about what a prime number is, and a cool video of Adam Spencer talking about "monster primes").
Alot of people think that number 1 is a prime number because the basic prime number rule is that the number can only be divided by itself and 1 (there are no other possible factors). In this case, 1 divided by itself = 1, but that is actually the exact reason it is not prime. In fact, even my sister's maths teacher was telling her class recently that 1 should be considered prime.
So why is 1 not prime? Because, as explained by my favourite mathematician Adam Spencer on the 26 June 2014 Sleek Geeks podcast The Number One, Big Data and Twittertime (you can find it on iTunes - just search up "Sleek Geeks" in Podcasts) no prime number multiplied by another prime number can be prime. Sounds a bit confusing, but if you think about 3, that is prime because it is 1x3, but that means one of factors cannot be prime. So we know 3 is prime, which means 1 cannot be. Also, 1x1 would be two prime numbers being multiplied, which does not fit the rule for "primacy". So that is why 1 is not a prime number.
For a bit more information on why 1 is not prime, check out this page, which gives more detail.
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