Which fingers are used to demonstrate Fleming's left-hand rule?

The fingers used to demonstrate Fleming's left-hand rule are the thumb, index/pointer finger, and middle finger.

According to Fleming's left-hand rule,  the thumb, forefinger and middle finger of your left hand are to be stretched such that they are perpendicular to each other.  If the first finger points in the direction of the magnetic field and the second finger in the direction of the current, then the thumb will point in the direction of motion or the force acting on the conductor.