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LCM and GCD Combo

Source: 2020 AMC 12A #21

January 31, 2020
AMCAMC 12number theoryleast common multiplegreatest common divisor2020 AMC 12A2020 AMC

Problem Statement

How many positive integers nn are there such that nn is a multiple of 55, and the least common multiple of 5!5! and nn equals 55 times the greatest common divisor of 10!10! and n?n?
<spanclass=latexbold>(A)</span>12<spanclass=latexbold>(B)</span>24<spanclass=latexbold>(C)</span>36<spanclass=latexbold>(D)</span>48<spanclass=latexbold>(E)</span>72<span class='latex-bold'>(A) </span> 12 \qquad <span class='latex-bold'>(B) </span> 24 \qquad <span class='latex-bold'>(C) </span> 36 \qquad <span class='latex-bold'>(D) </span> 48 \qquad <span class='latex-bold'>(E) </span> 72