+0  
 
0
555
8
avatar+124 

Find the greatest common factor of 210 and 90 

Brainfreezezeve  Dec 3, 2015

Best Answer 

 #7
avatar+20115 
+30

I do not get what you have done Heureka

 

\(\begin{array}{rcll} 210 & \color{blue}+++ & \color{blue}+++& \color{blue}+++ &\color{blue} +++ &\color{blue}+++ &\color{blue}+++ &\color{blue}+++ \\ -90 & \color{green}+++ & \color{green}+++& \color{green}+++ \\ = 120 & &&& \color{blue} +++ &\color{blue}+++ &\color{blue}+++ &\color{blue}+++ \\ \hline 120 & \color{blue} +++ &\color{blue}+++ &\color{blue}+++ &\color{blue}+++ \\ -90 & \color{green}+++ & \color{green}+++& \color{green}+++ \\ = 30 & &&& \color{blue} +++\\ \hline 90 & \color{green}+++ & \color{green}+++& \color{green}+++ \\ - 30 & \color{blue} +++\\ =60 & & \color{green}+++ & \color{green}+++ \\ \hline 60 & \color{green}+++ & \color{green}+++ \\ -30 & \color{blue} +++\\ 30 & & \color{green}+++\\ \hline 30 & \color{blue}+++\\ =30 & \color{green}+++\\ \end{array}\\ \begin{array}{rcl} \text{gcd}(210,90) = 30, \text{ because blue and green are equal} \end{array}\\\)

 

laugh

heureka  Dec 3, 2015
 #1
avatar+20115 
+20

Find the greatest common factor of 210 and 90 

 

\(\begin{array}{rcl} 210 - 90 &=& 120 \\ 120 - 90 &=& 30 \\ 90 - 30 &=& 60 \\ 60 - \mathbf{30} &=& \mathbf{30} \end{array}\\\)

 

The greatest common factor of 210 and 90 is 30

 

laugh

heureka  Dec 3, 2015
 #2
avatar+93866 
+10

BrainFreeze,

Are you even looking at the answers that you have already been given?

You have been logged on for hours but you have not responded to any of the answerers who have already tried to help you.

Maybe you can be more polite this time and show an interest in the answer that Heureka has prepared especially for you.

Melody  Dec 3, 2015
 #3
avatar+124 
0

oh thank you i've been doing it the hard way angrycheeky

Brainfreezezeve  Dec 3, 2015
 #4
avatar+124 
0

i've be logged on but i have not been in the tab sorry angryfrown

Brainfreezezeve  Dec 3, 2015
 #5
avatar+93866 
+10

ok no worries,

Do not forget to thank heureka :)

It is best to do it on the forum so everyone can see your good manners :)

Melody  Dec 3, 2015
 #6
avatar+93866 
0

 

I do not get what you have done Heureka   frown

Melody  Dec 3, 2015
 #7
avatar+20115 
+30
Best Answer

I do not get what you have done Heureka

 

\(\begin{array}{rcll} 210 & \color{blue}+++ & \color{blue}+++& \color{blue}+++ &\color{blue} +++ &\color{blue}+++ &\color{blue}+++ &\color{blue}+++ \\ -90 & \color{green}+++ & \color{green}+++& \color{green}+++ \\ = 120 & &&& \color{blue} +++ &\color{blue}+++ &\color{blue}+++ &\color{blue}+++ \\ \hline 120 & \color{blue} +++ &\color{blue}+++ &\color{blue}+++ &\color{blue}+++ \\ -90 & \color{green}+++ & \color{green}+++& \color{green}+++ \\ = 30 & &&& \color{blue} +++\\ \hline 90 & \color{green}+++ & \color{green}+++& \color{green}+++ \\ - 30 & \color{blue} +++\\ =60 & & \color{green}+++ & \color{green}+++ \\ \hline 60 & \color{green}+++ & \color{green}+++ \\ -30 & \color{blue} +++\\ 30 & & \color{green}+++\\ \hline 30 & \color{blue}+++\\ =30 & \color{green}+++\\ \end{array}\\ \begin{array}{rcl} \text{gcd}(210,90) = 30, \text{ because blue and green are equal} \end{array}\\\)

 

laugh

heureka  Dec 3, 2015
 #8
avatar+93866 
+5

Thanks Heureka,

 

I understand but it is still really weird.  I will muck around with it some more.

 

I would just have broken them into their prime factors.

I suppose your way is quicker.... I will have to think about it. ........

 

My way

 

90=10*9=2*5*3*3

210=10*21=2*5*3*7

 

so GCF=2*5*3 =30

Melody  Dec 3, 2015

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