Difference of LCMs

What is the difference when the LCM of the numbers from 1 1 to 53 53 is subtracted from the LCM of the numbers from 1 1 to 58 58 ?

lcm ( 1 , 2 , 3 , 4 , . . . , 58 ) lcm ( 1 , 2 , 3 , 4 , . . . , 53 ) \small \text{lcm}(1,2,3,4,...,58) - \text{lcm}(1,2,3,4,...,53)


Try another problem involving LCMs.


The answer is 0.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Kaizen Cyrus
Jun 4, 2020

To find the LCM of the numbers from 1 1 to 53 53 , we must find all largest p n p^{n} below 53 53 , where p p is a prime number, and multiply them. The same goes with the other sequence of numbers but all p n p^{n} must be below 58 58 .

List of prime numbers: 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 . . . \begin{array}{cccccc} 2 & 3 & 5 & 7 & 11 & 13 \\ 17 & 19 & 23 & 29 & 31 & 37 \\ 41 & 43 & 47 & 53 & 59 & ... \end{array}

The list above shows that the prime numbers from 53 53 below and from 58 58 below are the same. There are also no p n p^{n} that is between 53 53 and 58 58 , meaning the factors to make their LCMs are the same. Thus, their LCMs have a difference of 0 \boxed{0} .

Nice problem. I found this one quite elegant!

Mahdi Raza - 1 year ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...