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Number Theory Level 2

How many factors does 2015 have?


The answer is 8.

Andrew The by Andrew The , 25, USA

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1 solution

Ashwin Padaki
May 16, 2015

2015 = 5 * 13 * 31. We can either not include the 5, 13, 31, or a combination of them. If we don't include 5, we can have:

  • 13 * 31
  • 13
  • 31
  • 1

If we include 5, we have those same options. 4 * 2 = 8 {8}

0 Helpful 0 Interesting 0 Brilliant 0 Confused

This solution sucks. Either 5. 13, or 41 can be either a factor of a factor or not a factor of a factor. Thus, there are 2 3 = 8 2^3 = \boxed{8} factors.

Clive Chen - 3 years, 7 months ago

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