I've loved this visualization for Euclid's Algorithm since the first time I saw it... which might have been at NRICH. [url]http://nrich.maths.org/1357[/url][br][br]To me, the rectangle visualization helps to understand what is going on, why the algorithm works, why the quotients and remainders are significant.[br][br]In this visualization you can also see how robust the algorithm is, and how quickly it converges to greatest common divisor.[br][br]Note that occasionally one of the sets of squares disappears, for no reason that I can find! Try another number or reset the sketch.

More GeoGebra at [url]mathhombre.blogspot.com/p/geogebra.html[/url].