Happy New Year 2009, everyone! I am curious: is 2009 a prime number? If not, what is it a multiple of?
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Grandma Roses - my avatar is my real dog
ANSWERS: 6
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2009 = 7 x 7 x 41 http://www.apples4theteacher.com/prime-factors.html?num=2009&worksp=
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It's not a prime number; it's multiples are 7 & 287. Here's the tool I used (the formulas are way over my head): http://primes.utm.edu/curios/includes/primetest.php The site (http://primes.utm.edu) is devoted to prime numbers.
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How to find factor of a number N. First, a quick 2,3,5 test: If the number is even, it has a factor of 2. If the "digital root" of the number is divisible by 3, it has a factor of 3. The digital root is what you get when you repeatedly add up the digts until you are left with just one digit. If the number ends in 5, it has a factor of 5. Plan to divide prime numbers starting at 7 each into N, one by one. If you keep doing this and fail to find a divisor before the divisor exceeds the quotient, then the number is prime. 2009: not even, doesn't end in 5, digital root = 2 which is not a multiple of 3. 7 into 2009 is 287 repeat: 287: not even, doesn't end in 5, digital root = 8 which is not a multiple of 3. 7 into 287 is 41 repeat: 41: not even, doesn't end in 5, digital root = 5 which is not a multiple of 3. 7 into 41 is 5pointsomething which is less than 7 so 41 is prime.
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No: 7 goes into it 287 times
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It's past
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Thank you. I don't know.
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