Find Greatest Common Divisor of 504 and 980, using prime factorization.

Step 1 : Find prime factorization of each number.

$$\begin{aligned}504 =& 2\cdot2\cdot2\cdot3\cdot3\cdot7\\[8pt]980 =& 2\cdot2\cdot5\cdot7\cdot7\\[8pt]\end{aligned}$$

(view steps on how to factor 504 and 980. )

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

$$\begin{aligned}504 =& \color{blue}{\boxed{2}}\cdot\color{red}{\boxed{2}}\cdot2\cdot3\cdot3\cdot\color{Fuchsia}{\boxed{7}}\\[8pt]980 =& \color{blue}{\boxed{2}}\cdot\color{red}{\boxed{2}}\cdot5\cdot\color{Fuchsia}{\boxed{7}}\cdot7\\[8pt]\end{aligned}$$

Step 3 : Multiply the boxed numbers together:

$$ GCD = 2\cdot2\cdot7 = 28 $$

This solution can be visualized using a Venn diagram.

The GCD equals the product of the numbers at the intersection.

GCD Calculator