Would Factoring 180 Help?

The product of 180 and a positive integer N N is a perfect cube . What is the least possible value of N N ?


The answer is 150.

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3 solutions

Relevant wiki: Perfect Squares, Cubes, and Powers

180 = 2 2 × 3 2 × 5 180=2^2×3^2×5 .

Since the product is a perfect cube, each of the exponents must be a multiple of 3.

Therefore the least value of N N is 2 × 3 × 5 2 = 150 2×3×5^2=\boxed{150} .

@Hummus a I didn't get the title .

Keshav Tiwari - 5 years ago

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It was meant to pose the question if such N N exists,or that all N N multiplied by 180 wouldn't give a perfect cube.It was meant to be to the less advanced solvers,which you are way beyond! :)

Hamza A - 5 years ago

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Oh ! Thanks btw you are really good at calculus.

Keshav Tiwari - 5 years ago

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@Keshav Tiwari Thanks!(extension because thanks apparently isn't enough to write XD)

Hamza A - 5 years ago
Sudoku Subbu
Jul 3, 2016

Given, The product of 180 and a positive integer N is a perfect cube. Let 180 × N = x 3 180\times N \space = \space x^3 = > 2 2 × 3 2 × 5 1 × N = x 3 => \space 2^2\times3^2\times5^1\times N=x^3 There for the product to be a perfect cube, The value of N N must be 2 1 × 3 1 × 5 2 2^1\times3^1\times5^2 = 150 150

  • First convert the original number to its factors. 180=2 2 3 3 5
  • Then you have to complete series of three numbers. So because there are two 2s, use one more 2; because there are two 3s, use one more 3; and because there is one 5, use two more 5s.
  • Then multiply the numbers that you used 2 3 5*5=150
  • At the end you'll have the product of 180 150, and because it's made only by series of three numbers (2 2 2, 3 3 3 and 5 5*5) you now that is a perfect cube.

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