All this is done with an upward movement of the hand and forearm. The thumbnail strikes the part of the coin unsupported by the index finger, sending it rotating upward.
The coin is initially placed on a bent forefinger, and the thumb is released from under the coin surface, where it has been held under tension. When a coin is flipped into the air, it is supposedly made to rotate about an axis parallel to its flat surfaces. (Research suggests that when the coin is allowed to fall onto a hard surface, the chance of this happening is in the order of 1 in 6000 tosses. There are only 2 possible outcomes, “heads” or “tails,” although, in theory, landing on an edge is possible.
This method may be used to resolve a dispute, see who goes first in a game or determine which type of treatment a patient receives in a clinical trial. The toss or flip of a coin to randomly assign a decision traditionally involves throwing a coin into the air and seeing which side lands facing up.
