Question
Find Greatest Common Divisor of 220 and 231, using prime factorization.
Answer
The GCD of given numbers is 11.
Explanation
Step 1 : Find prime factorization of each number.
$$\begin{aligned}220 =& 2\cdot2\cdot5\cdot11\\[8pt]231 =& 3\cdot7\cdot11\\[8pt]\end{aligned}$$(view steps on how to factor 220 and 231. )
Step 2 : Put a box around factors that are common for all numbers:
$$\begin{aligned}220 =& 2\cdot2\cdot5\cdot\color{blue}{\boxed{11}}\\[8pt]231 =& 3\cdot7\cdot\color{blue}{\boxed{11}}\\[8pt]\end{aligned}$$Step 3 : Multiply the boxed numbers together:
$$ GCD = 11 $$This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.
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