Find Greatest Common Divisor of 9, 30, 39, 49, 59 and 21, using prime factorization.
Answer
The GCD of given numbers is 1.
Explanation
Step 1 : Find prime factorization of each number.
$$\begin{aligned}9 =& 3\cdot3\\[8pt]30 =& 2\cdot3\cdot5\\[8pt]39 =& 3\cdot13\\[8pt]49 =& 7\cdot7\\[8pt]59 =& 59\\[8pt]21 =& 3\cdot7\\[8pt]\end{aligned}$$(view steps on how to factor 9, 30, 39, 49, 59 and 21. )
Step 2 : Put a box around factors that are common for all numbers:
$$\begin{aligned}9 =& 3\cdot3\\[8pt]30 =& 2\cdot3\cdot5\\[8pt]39 =& 3\cdot13\\[8pt]49 =& 7\cdot7\\[8pt]59 =& 59\\[8pt]21 =& 3\cdot7\\[8pt]\end{aligned}$$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} } $.
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