The GCD of given numbers is 2.
Step 1 : Find prime factorization of each number.
$$\begin{aligned}28 =& 2\cdot2\cdot7\\[8pt]38 =& 2\cdot19\\[8pt]52 =& 2\cdot2\cdot13\\[8pt]54 =& 2\cdot3\cdot3\cdot3\\[8pt]68 =& 2\cdot2\cdot17\\[8pt]8 =& 2\cdot2\cdot2\\[8pt]\end{aligned}$$(view steps on how to factor 28, 38, 52, 54, 68 and 8. )
Step 2 : Put a box around factors that are common for all numbers:
$$\begin{aligned}28 =& \color{blue}{\boxed{2}}\cdot2\cdot7\\[8pt]38 =& \color{blue}{\boxed{2}}\cdot19\\[8pt]52 =& \color{blue}{\boxed{2}}\cdot2\cdot13\\[8pt]54 =& \color{blue}{\boxed{2}}\cdot3\cdot3\cdot3\\[8pt]68 =& \color{blue}{\boxed{2}}\cdot2\cdot17\\[8pt]8 =& \color{blue}{\boxed{2}}\cdot2\cdot2\\[8pt]\end{aligned}$$Step 3 : Multiply the boxed numbers together:
$$ GCD = 2 $$