MathDB
Turkey NMO 2010 1st Round - P10 (Number Theory)

Source:

July 27, 2012
modular arithmetic

Problem Statement

How many integers nn with 0n<8400\leq n < 840 are there such that 840840 divides n8n4+n1n^8-n^4+n-1?
<spanclass=latexbold>(A)</span> 1<spanclass=latexbold>(B)</span> 2<spanclass=latexbold>(C)</span> 3<spanclass=latexbold>(D)</span> 6<spanclass=latexbold>(E)</span> 8 <span class='latex-bold'>(A)</span>\ 1 \qquad<span class='latex-bold'>(B)</span>\ 2 \qquad<span class='latex-bold'>(C)</span>\ 3 \qquad<span class='latex-bold'>(D)</span>\ 6 \qquad<span class='latex-bold'>(E)</span>\ 8