perplexus.info :: Numbers : Increase in number of factors.

Increase in number of factors. (Posted on 2010-10-05)

If n has 15 factors (1 and n inclusive ) and 2n has 20 factors. What is the number of factors of 4n?

Also, what can be the number of factors of 5n ?

See The Solution Submitted by Vishal Gupta

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Puzzle Answer

Comment 5 of 5 |

4n will have precisely 25 factors.

5n will have:

30 factors if a power of 5 does NOT divide n.

18 factors if a power of 5 divides n.

Posted by K Sengupta on 2022-07-10 21:26:19

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