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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,638

Some animations about getting a Common Denominator

Thoughts?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,575

Excellent animation! Very well created!

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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**mikau****Member**- Registered: 2005-08-22
- Posts: 1,504

hmm... to be honest I find it a little confusing.

In my oppinion it would clearer, if you did it this way

1/3 + 1/5, the first step is to write the cross product as the numerator of the sum

(1*5 + 3*1) then draw a line beneath it, and write the denominator of the sum as the product of the two denominators. (1*5+3*1)/(3*5) = 8/15

I just think its more straightforward. Does anyone agree?

*Last edited by mikau (2007-08-22 06:35:37)*

A logarithm is just a misspelled algorithm.

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**mikau****Member**- Registered: 2005-08-22
- Posts: 1,504

but i probably only prefer that because thats how I add fractions.

A logarithm is just a misspelled algorithm.

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**John E. Franklin****Member**- Registered: 2005-08-29
- Posts: 3,588

mikau, that's cool but mif's thing is the standard way I learned, so it looks easy to me.

To critique it well, you have to pretend you don't know how to do it, and watch it.

I'll watch again and pretend...

After watching a few times, the only minor thing is that you might want to

erase the green highlight before drawing the lavender highlight to the right,

so you can see it better. If it is possible.

*Last edited by John E. Franklin (2007-08-22 15:09:57)*

**igloo** **myrtilles** **fourmis**

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,638

mikau wrote:

(1*5 + 3*1) then draw a line beneath it, and write the denominator of the sum as the product of the two denominators. (1*5+3*1)/(3*5) = 8/15

That is actually quicker, but I am building on the concept of Equivalent Fractions (http://www.mathsisfun.com/equivalent_fractions.html) so want to keep it along those lines.

Maybe I could have an animation "quick method" ... ?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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