Comments on: Brain Game: A Factor Fact

By: Michael

Michael — Thu, 01 Jan 2009 11:07:00 +0000

Scratch that–it would be even lower than -6. It would be the lowest negative number with 8 factors, whatever that might be. *is embarrassed*

By: Michael

Michael — Thu, 01 Jan 2009 11:05:00 +0000

I learned this little caveat early on: Make sure you ask for a positive number. Otherwise, the correct answer would be -6 (Factors are -6, -3, -2, -1, 1, 2, 3, and 6).

By: Matt

Matt — Tue, 30 Dec 2008 22:19:00 +0000

Eric,

Not to get too ticky-tacky, but isn’t the least common denominator of x/2, x/3, and x/4 “12″?

That being said, the lowest common denominator of x/2, x/3 and x/4 that does not result in a quotient of {2,3,4} when divided by {2,3,4} is 24.

By: Eric

Eric — Tue, 30 Dec 2008 18:57:00 +0000

Doh, I meant square numbers anyway, not prime.

By: Bryan

Bryan — Tue, 30 Dec 2008 17:55:00 +0000

Eric,

Perhaps a typo. Squares have an odd number of factors. Primes have two factors.

Your solution was much more elegant than mine. I used Excel to count factors. It works for small numbers, but would be awkward if they asked for the smallest number with 30 factors.

By: Eric

Eric — Tue, 30 Dec 2008 16:16:00 +0000

Forgot the reCaptcha. I apologize if my first comment shows anwyay:

Actually figured it out! I knew it couldn’t have been a prime number, else there’d be an odd number of factors. I let x be the solution, and looked at pairs of factors: 1 and x are two of the factors, I assumed 2 and x/2 were 2 more factors, 3 and x/3, and finally 4 and x/4. What is x? The least common denominator of x/2, x/3, and x/4 = 24. :) My math degree is finally paying off.

By: jen

jen — Tue, 30 Dec 2008 15:27:00 +0000

I knew it was 24 without having to think about it…then again I just finished teaching factors to my 4th graders!

By: Jack

Jack — Tue, 30 Dec 2008 12:43:00 +0000

go go 24.