Divide the Pyramid

Level 2

The n t h n^{th} square pyramidal number is equal to the sum of all perfect squares up to and including n 2 n^{2} .

What is the highest power of 2018 2018 that will divide into the 4930769899 2 t h 49307698992^{th} square pyramidal number?


The answer is 3.

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

The n t h n^{th} square pyramidal number can be found by using i = 1 n i 2 = ( n ) ( n + 1 ) ( 2 n + 1 ) 6 \sum_{i = 1} ^{n}i^2 = \frac{(n)(n+1)(2n+1)}{6} . Prime factorzing 49307698992 49307698992 leads to 49307698992 = 6 201 8 3 49307698992 = 6*2018^{3} n = 6 201 8 3 n = 6*2018^{3} Thus let P = 6 201 8 3 P = 6*2018^{3} pyramidal number which means P = ( 6 201 8 3 ) ( 6 201 8 3 + 1 ) ( 2 ( 6 201 8 3 ) + 1 ) 6 P =\frac{(6*2018^{3})(6*2018^{3}+1)(2(6*2018^{3})+1)}{6} Let m m be the maximum number whereby 201 8 m P 2018^{m} \:| \;P . Simplifying P P = ( 201 8 3 ) ( 6 201 8 3 + 1 ) ( 2 ( 6 201 8 3 ) + 1 ) P =(2018^{3})(6*2018^{3}+1)(2(6*2018^{3})+1) We then want to find 201 8 m ( 201 8 3 ) ( 6 201 8 3 + 1 ) ( 2 ( 6 201 8 3 ) + 1 ) 2018^{m} \; | \; (2018^{3})(6*2018^{3}+1)(2(6*2018^{3})+1) Clearly, the highest power of 2018 2018 that divides P P is 3 \boxed{3} because of the first term. The second and third term both are not divisible by 2018 2018 .

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...