Difference between revisions of "2013 UNCO Math Contest II Problems/Problem 2"

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EXAMPLE: The number <math>64</math> is equal to <math>8^2</math> and also equal to <math>4^3</math>, so <math>64</math> is both a perfect square and a perfect cube.
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EXAMPLE: The number <math>64</math> is equal to <math>8^2</math> and also equal to <math>4^3</math>, so <math>64</math> is both a perfect square and a perfect cube poop is awesome
  
 
(a) Find the smallest positive integer multiple of <math>12</math> that is a perfect square.
 
(a) Find the smallest positive integer multiple of <math>12</math> that is a perfect square.

Revision as of 20:12, 4 May 2020

Problem

EXAMPLE: The number $64$ is equal to $8^2$ and also equal to $4^3$, so $64$ is both a perfect square and a perfect cube poop is awesome

(a) Find the smallest positive integer multiple of $12$ that is a perfect square.

(b) Find the smallest positive integer multiple of $12$ that is a perfect cube.

(c) Find the smallest positive integer multiple of $12$ that is both a perfect square and a perfect cube.

Solution

We can factor 12 into 2*2*3. There are already two factors of two, so we only need to multiply it by 3 to get two factors of three, giving us 36.


To find the perfect cube, we need all of the prime factors to be to the third power. Because 2 is squared, we need to multiply by a power of 2, giving us 2*12=24. Because we only have one power of three, we need two more, so we multiply 24*3*3, giving us 216, which is a perfect cube.

To find a perfect 6th power, we multiply 36*216 to get 7776. We know that the factorization of this number is 2^5*3^5. This means that this number is 6^5. We need a perfect 6th, so we multiply by 6 to get 46656, which is 6^6.

See Also

2013 UNCO Math Contest II (ProblemsAnswer KeyResources)
Preceded by
Problem 1
Followed by
Problem 3
1 2 3 4 5 6 7 8 9 10
All UNCO Math Contest Problems and Solutions