MathDB
Positive Cubes Divide Factorial Expression

Source:

January 12, 2009
geometry3D geometryfactorialmodular arithmeticAMCAIMEnumber theory

Problem Statement

How many positive integer cubes divide 3!5!7! 3!\cdot 5!\cdot 7!? <spanclass=latexbold>(A)</span> 2<spanclass=latexbold>(B)</span> 3<spanclass=latexbold>(C)</span> 4<spanclass=latexbold>(D)</span> 5<spanclass=latexbold>(E)</span> 6 <span class='latex-bold'>(A)</span>\ 2\qquad <span class='latex-bold'>(B)</span>\ 3\qquad <span class='latex-bold'>(C)</span>\ 4\qquad <span class='latex-bold'>(D)</span>\ 5\qquad <span class='latex-bold'>(E)</span>\ 6