The GCD of given numbers is 61.
Step 1 : Find prime factorization of each number.
$$\begin{aligned}122 =& 2\cdot61\\[8pt]427 =& 7\cdot61\\[8pt]\end{aligned}$$(view steps on how to factor 122 and 427. )
Step 2 : Put a box around factors that are common for all numbers:
$$\begin{aligned}122 =& 2\cdot\color{blue}{\boxed{61}}\\[8pt]427 =& 7\cdot\color{blue}{\boxed{61}}\\[8pt]\end{aligned}$$Step 3 : Multiply the boxed numbers together:
$$ GCD = 61 $$This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.