Re: tell me if this is right.

From: slag (rob_at_robfindlay.org)
Date: 07/15/04 

Date: 15 Jul 2004 07:42:55 -0700

LarryLard wrote:
> "slag" <rob@robfindlay.org> wrote in message
news:<cd4hrf$8j7@odak26.prod.google.com>...
> [snip]
> > (V) Add and and reduce.
> >
> > = 13,142/15,048
> >
> >
> > Now to reduce i've applied the Euclidean algorithm
>
> Before explicitly finding the GCD, it's worth checking if you can see
> any common factors 'by inspection' (ie, by looking :)). Here it's
easy
> to see that numerator and denominator share a common factor of 2
> (since they are both even), so we can immediately say
>
> 13142/15048 = 6571/7524

Yeah i've forgotten those tricks. Any number ending in an even number
or zero is even and therefore divisable by 2 and in the case of 5 or 0
divisable by 5.

> which gives us a head start in the Euclidean GCD algorithm.
Obviously,
> common factors of 2 and 5 are the easiest to see by inspection; there
> are 'quick' methods for spotting divisibility by 3, 9, and 11 as well
> (and others maybe)

What are the tricks for 3, 9, 11 ?

> Has anyone suggested newsgroup alt.algebra.help to you? You will find
> less 'noise' than sci.math there.

I'll give it a look see tkns!
> --
> Larry Lard
> Replies to group please.

Rob Findlay

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