Unicorns to horses
Oh no! An evil wizard is rounding up all the unicorns in the world and turning them into horses! Luckily, some unicorns are immune to his evil spell...
Count the unicorns entering the wizard's temple and then the horses going out of it. How many unicorns are still there after each batch is processed?
Based on the math mini-game "Alien Abduction" - part of the game "Brain Champion" for Nokia mobile phones (http://store.ovi.com/content/101442?clickSource=related%2Bcontent&contentArea=games&pos=7).
Background - "Barn Beat" from www.SoundJay.com (http://www.soundjay.com/free-music-2.html).
Success sound made by grunz; available from here: http://www.freesound.org/people/grunz/sounds/109662/
Failure sound made by Splashdust; available from here: http://www.freesound.org/people/Splashdust/sounds/84327/