The GCD of given numbers is 99.
Step 1 : Find prime factorization of each number.
$$\begin{aligned}1485 =& 3\cdot3\cdot3\cdot5\cdot11\\[8pt]4356 =& 2\cdot2\cdot3\cdot3\cdot11\cdot11\\[8pt]\end{aligned}$$(view steps on how to factor 1485 and 4356. )
Step 2 : Put a box around factors that are common for all numbers:
$$\begin{aligned}1485 =& \color{blue}{\boxed{3}}\cdot\color{red}{\boxed{3}}\cdot3\cdot5\cdot\color{Fuchsia}{\boxed{11}}\\[8pt]4356 =& 2\cdot2\cdot\color{blue}{\boxed{3}}\cdot\color{red}{\boxed{3}}\cdot\color{Fuchsia}{\boxed{11}}\cdot11\\[8pt]\end{aligned}$$Step 3 : Multiply the boxed numbers together:
$$ GCD = 3\cdot3\cdot11 = 99 $$This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.