How to use a small electric motor controller?

I would like to have a small electric motor turn exactly 6 rotations each time a press a switch (button). Should I use a servo or motor? What type of motor controller should I use?
Is it possible to have a power switch that you can adjust how much power comes through?

I think there are different options.

So far as I am aware RC servos typically turn only a fraction of a rotation.

A small gear head motor could be used but you would need some feedback to know when to stop the rotation.

http://www.solarbotics.com/products/index.php?scdfa-250100084-viewCategory-categoryzq37=true&frm=sbbi

A stepper motor may be more straight forward for you (especially since you say you need “exactly 6 rotations”).

http://en.wikipedia.org/wiki/Stepper_motor

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