Step 1 : Find prime factorization of each number.

$$\begin{aligned}328 =& 2\cdot2\cdot2\cdot41\\[8pt]769 =& 769\\[8pt]541 =& 541\\[8pt]986 =& 2\cdot17\cdot29\\[8pt]215 =& 5\cdot43\\[8pt]734 =& 2\cdot367\\[8pt]\end{aligned}$$

(view steps on how to factor 328, 769, 541, 986, 215 and 734. )

Step 2 : Put a box around factors that are common for all numbers:

$$\begin{aligned}328 =& 2\cdot2\cdot2\cdot41\\[8pt]769 =& 769\\[8pt]541 =& 541\\[8pt]986 =& 2\cdot17\cdot29\\[8pt]215 =& 5\cdot43\\[8pt]734 =& 2\cdot367\\[8pt]\end{aligned}$$

Note that in this example numbers do not have any common factors.

Step 3 : Multiply the boxed numbers together:

Since there is no boxed numbers we conclude that $~\color{blue}{ \text{GCD = 1} } $.

GCD Calculator