Question

qual o mdc de 21,63 e 105

Answer 1

MDC = máximo divisor comum 

Para encontrá-lo basta decompormos e observarmos quis dividem ambos ao mesmo tempo ... 

Decompondo ... 

21 , 63 , 105/3
7 , 21 , 35/3
7, 7 , 35/5
7 , 7 ,7/7
1 , 1 , 1 

MDC = 3 x 7 = 21                                                        ok  

Answer 2

$\large{\begin{array}{c c c|l}21&63&105&\Large\textcircled{\normalsize3}\\7&21&35&\:\,3\\7&7&35&\,\:5\\7&7&7&\Large\textcircled{\normalsize 7}\\1&1&1\end{array}}$

$\red{\boldsymbol{MDC(21,63,105)=21}}$