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The number of positive integers that divide \((1890) \cdot (130) \cdot (170)\) and are not divisible by \(45\) is

Question and options

The number of positive integers that divide (1890)⋅(130)⋅(170)(1890) \cdot (130) \cdot (170) and are not divisible by 4545 is
  1. 320
  2. 416
  3. 192
  4. 512

Answer and explanation

Correct answer: A - 320

There are 320320 eligible divisors. The product is 23⋅33⋅53⋅7⋅13⋅172^3\cdot3^3\cdot5^3\cdot7\cdot13\cdot17, giving 43⋅23=5124^3\cdot2^3=512 divisors in all. A multiple of 4545 has two choices for the exponent of 33, three for the exponent of 55, and 4⋅234\cdot2^3 choices for the remaining exponents, so subtract 192192 from 512512. Reporting 192192 counts the excluded divisors.

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  • IPMAT Indore

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