Find Greatest Common Divisor of 72 and 124, using prime factorization.
Answer
The GCD of given numbers is 4.
Explanation
Step 1 : Find prime factorization of each number.
$$\begin{aligned}72 =& 2\cdot2\cdot2\cdot3\cdot3\\[8pt]124 =& 2\cdot2\cdot31\\[8pt]\end{aligned}$$(view steps on how to factor 72 and 124. )
Step 2 : Put a box around factors that are common for all numbers:
$$\begin{aligned}72 =& \color{blue}{\boxed{2}}\cdot\color{red}{\boxed{2}}\cdot2\cdot3\cdot3\\[8pt]124 =& \color{blue}{\boxed{2}}\cdot\color{red}{\boxed{2}}\cdot31\\[8pt]\end{aligned}$$Step 3 : Multiply the boxed numbers together:
$$ GCD = 2\cdot2 = 4 $$This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.
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