Please explain why. you think this.
Make the answer simple.
Thnx!
2007-10-18 10:04:56 · 9 answers · asked by Someone 2 in Science & Mathematics ➔ Mathematics
No, (in fact, not only can you say that "not all odd numbers are prime", but you can make the stronger statement that "MOST odd numbers are NOT prime"), and any of the counter examples given by the answers above are proof enough of this fact. However, the converse of this is mostly true, that is, all prime numbers are odd (except for one of them, namely 2); for if a number was even, it would have a factor of 2 and thus not prime.
Another (and perhaps easier) way to look at it is this:
take any two odd primes and multiply them together.
The result is odd, and clearly not prime!
2007-10-18 10:23:42 · answer #1 · answered by Scott R 6 · 1⤊ 0⤋
9 = 3 x 3 so 9 is not prime
15 = 3 x 5 so 15 is not prime
etc etc
All odd numbers are not prime.
2007-10-19 02:43:13 · answer #2 · answered by Como 7 · 0⤊ 0⤋
no.
21 is an odd number, and it is divisible by 1, 3, 7, and 21.
Now, 3 is odd, but it cannot be divided by anything other than itself and 1.
So, no. Not all odd numbers are prime.
2007-10-18 10:15:38 · answer #3 · answered by OtakuMania! 2 · 0⤊ 0⤋
Just think of some examples of odd numbers...1,3,5,7,9
Nine is odd but is not prime. Same for 15, 21, 27 and other multiples of 3.
2007-10-18 10:10:37 · answer #4 · answered by Anonymous · 0⤊ 0⤋
No, not all odd numbers are prime.
a prime number (or a prime) is a natural number which has exactly two distinct natural number divisors: 1 and itself.
So, 5 would be prime, but 9 wouldn't.
(5 is divisible by itself and 1.)
(9 is divisible by itself and 1 AS WELL AS 3 and 3.)
2007-10-18 10:11:30 · answer #5 · answered by anjlbeing 3 · 0⤊ 0⤋
No. A prime number is one which can only be devided by itself and one.
For instance 9 is divisible by 3 therefore is NOT a prime number.
15, 25, 35, 45, etc. divisible by 5
21, 35, etc. divisible by 7
You get the idea.
2007-10-18 10:09:47 · answer #6 · answered by lou t 1 · 1⤊ 0⤋
no , not all odd numbers are prime
1,3,5,7 are prime because they are only 1 x itself
9 is an odd number 1,3,9 1x9 3x3 composite not prime
2007-10-18 10:10:09 · answer #7 · answered by Dave aka Spider Monkey 7 · 0⤊ 0⤋
no. 27 is odd but its not prime. so is 81
2007-10-18 10:09:33 · answer #8 · answered by Armine 3 · 0⤊ 0⤋
i don't think so, because 9, 27, 33 are all odd numbers and they have factors.
2007-10-18 10:17:32 · answer #9 · answered by justme 3 · 0⤊ 0⤋