Editing Shuffling (section)

==Techniques==

===Overhand===
[[File:Overhand3.jpg|thumb|Overhand shuffle]]
One of the easiest shuffles to accomplish after a little practice is the '''overhand shuffle.''' Johan Jonasson wrote, "The overhand shuffle... is the shuffling technique where you gradually transfer the deck from, say, your right hand to your left hand by sliding off small packets from the top of the deck with your thumb."<ref>{{cite journal| title = The overhand shuffle mixes in Θ(n2logn) steps| year = 2006| doi = 10.1214/105051605000000692| arxiv = math/0501401| last1 = Jonasson| first1 = Johan| journal = The Annals of Applied Probability| volume = 16| s2cid = 119648392}}</ref> In detail as normally performed, with the pack initially held in the left hand (say), most of the cards are grasped as a group from the bottom of the pack between the thumb and fingers of the right hand and lifted clear of the small group that remains in the left hand. Small packets are then released from the right hand a packet at a time so that they drop on the top of the pack accumulating in the left hand.  The process is repeated several times. The randomness of the whole shuffle is increased by the number of small packets in each shuffle and the number of repeat shuffles performed.

The overhand shuffle offers sufficient opportunity for sleight of hand techniques to be used to affect the ordering of cards, creating a stacked deck. The most common way that players cheat with the overhand shuffle is by having a card at the top or bottom of the pack that they require, and then slipping it to the bottom at the start of a shuffle (if it was on top to start), or leaving it as the last card in a shuffle and just dropping it on top (if it was originally on the bottom of the deck).

===Riffle===
[[File:Riffle Shuffle.jpg|thumb|right|Cards lifted after a riffle shuffle, forming what is called a bridge which puts the cards back into place]]
[[File:Riffle shuffle 1.jpg|thumb|right|After a riffle shuffle, the cards cascade]]
A common shuffling technique is called the ''riffle,'' or ''dovetail'' shuffle or ''leafing the cards'', in which half of the deck is held in each hand with the thumbs inward, then cards are released by the thumbs so that they fall to the table interleaved. Many also lift the cards up after a riffle, forming what is called a bridge which puts the cards back into place; it can also be done by placing the halves flat on the table with their rear corners touching, then lifting the back edges with the thumbs while pushing the halves together. While this method is more difficult, it is often used in [[casino]]s because it minimizes the risk of exposing cards during the shuffle. There are two types of perfect riffle shuffles: if the top card moves to be second from the top then it is an [[in shuffle]], otherwise it is known as an [[out shuffle]] (which preserves both the top and bottom cards).

The [[Gilbert–Shannon–Reeds model]] provides a mathematical model of the random outcomes of riffling that has been shown experimentally to be a good fit to human shuffling<ref>{{citation
 | last = Diaconis | first = Persi | author-link = Persi Diaconis
 | isbn = 0-940600-14-5
 | location = Hayward, CA
 | mr = 964069
 | publisher = Institute of Mathematical Statistics
 | series = Institute of Mathematical Statistics Lecture Notes—Monograph Series, 11
 | title = Group representations in probability and statistics
 | year = 1988}}.</ref> and that forms the basis for a recommendation that card decks be riffled seven times in order to randomize them thoroughly.<ref>{{cite news |title=In Shuffling Cards, 7 Is Winning Number|first=Gina|last=Kolata|author-link=Gina Kolata |work=[[The New York Times]]|url=https://www.nytimes.com/1990/01/09/science/in-shuffling-cards-7-is-winning-number.html|date=January 9, 1990}}.</ref> Later, mathematicians [[Lloyd M. Trefethen]] and [[Lloyd N. Trefethen]] authored a paper using a tweaked version of the Gilbert–Shannon–Reeds model showing that the minimum number of riffles for total randomization could also be six, if the method of defining randomness is changed.<ref>{{cite news |title=Shuffling, what's the Deal? |url=https://www.nature.com/news/2000/001005/full/news001005-8.html}}</ref>{{sfn|Trefethen|Trefethen|2000}}

===Box===
Also known as "strip." The deck is held from the top by one hand close to the top of the table, and a pile is stripped off the top of the deck with the other hand and placed on the table. Additional piles are stripped off and placed on top of the previous pile until all cards have been placed onto the new pile. Boxing the cards is functionally the same as an overhand shuffle, however, by keeping the cards close to the table, it is less likely that cards will be accidentally exposed.

===Hindu===
Also known as the "Indian", "Kattar", "Kenchi" ([[Hindi]] for scissor) or "Kutti Shuffle". The deck is held face down, with the middle finger on one long edge and the thumb on the other on the bottom half of the deck. The other hand draws off a packet from the top of the deck. This packet is allowed to drop into the palm. The maneuver is repeated over and over, with newly drawn packets dropping onto previous ones, until the deck is all in the second hand. Indian shuffle differs from stripping in that all the action is in the hand ''taking'' the cards, whereas in stripping, the action is performed by the hand with the original deck, ''giving'' the cards to the resulting pile. This is the most common shuffling technique in Asia and other parts of the world, while the overhand shuffle is primarily used in Western countries.

===Pile===
Cards are simply dealt out into a number of piles, then the piles are stacked on top of each other. Though this is deterministic and does not randomize the cards at all, it ensures that cards that were next to each other are now separated. Some variations on the pile shuffle attempt to make it slightly random by dealing to the piles in a random order each circuit.

===52 pickup===
{{main|52 pickup}}
A person may throw a deck of cards into the air or across a surface, and then pick up the cards in random order, assembled with the cards facing the same direction. If specific cards are observed too closely as they are picked up, an additional 52 pickup or an additional shuffling method may be needed for sufficient randomization. This method is useful for beginners, but the shuffle requires a large clean surface for spreading out the cards, and it may take more time than is desired.  

'A game of 52 pickup' is also the name of a child's prank, where one child asks a 'friend' if they want to play 52 pickup.  They then throw the cards into the air, and demand the other child 'pick them up'.

===Corgi===
This method is similar to 52 pickup and also useful for beginners. Also known as the Chemmy, Irish, wash, scramble, hard shuffle, smooshing, schwirsheling{{Citation needed|date=April 2025}}, or washing the cards, this involves simply spreading the cards out face down, and sliding them around and over each other with one's hands. Then the cards are moved into one pile so that they begin to intertwine and are then arranged back into a stack. Statistically random shuffling is achieved after approximately one minute of smooshing. Smooshing has been largely popularized by Simon Hofman.<ref>{{cite arXiv| last1 = Diaconis| first1 = Persi| last2 = Pal| first2 = Soumik| title = Shuffling cards by spatial motion| date = 2017-11-02| class = math.PR| eprint = 1708.08147}}</ref>

===Mongean ===
The Mongean shuffle, or Monge's shuffle, is performed as follows (by a right-handed person): Start with the unshuffled deck in the left hand and transfer the top card to the right. Then repeatedly take the top card from the left hand and transfer it to the right, putting the second card at the top of the new deck, the third at the bottom, the fourth at the top, the fifth at the bottom, etc. The result, if one started with cards numbered consecutively <math>\scriptstyle 1, 2, 3, 4, 5, 6, \dots, 2n</math>, would be a deck with the cards in the following order: <math>\scriptstyle 2n, 2n-2, 2n-4, \dots, 4, 2, 1, 3, \dots, 2n-3, 2n-1</math>.

===Faro===
{{main|Faro shuffle}}
Weaving is the procedure of pushing the ends of two halves of a deck against each other in such a way that they naturally intertwine.  Sometimes the deck is split into equal halves of 26 cards which are then pushed together in a certain way so as to make them perfectly interweave. This is known as a ''Faro Shuffle''.

The [[faro shuffle]] is performed by cutting the deck into two, preferably equal, packs in both hands as follows (right-handed):
The cards are held from above in the right and from below in the left hand. Separation of the deck is done simply lifting up half the cards with the right hand thumb slightly and pushing the left hand's packet forward away from the right hand. The two packets are often crossed and tapped against each other to align them. They are then pushed together by the short sides and bent (either up or down). The cards then alternately fall into each other, much like a [[zipper]]. A flourish can be added by springing the packets together by applying pressure and bending them from above, as called the bridge finish. The faro is a controlled shuffle which does not randomize a deck when performed properly.

A perfect faro shuffle, where the cards are perfectly alternated, is considered one of the most difficult sleights by card magicians, simply because it requires the shuffler to be able to cut the deck into two equal packets and apply just the right amount of pressure when pushing the cards into each other. Performing eight perfect faro shuffles in a row restores the order of the deck to the original order only if there are 52 cards in the deck and if the original top and bottom cards remain in their positions (1st and 52nd) during the eight shuffles. If the top and bottom cards are weaved in during each shuffle, it takes 52 shuffles to return the deck back into original order (or 26 shuffles to reverse the order).

===Mexican spiral===
The Mexican spiral shuffle is performed by cyclic actions of moving the top card onto the table, then the new top card under the deck, the next onto the table, next under the deck, and so on until the last card is dealt onto the table. It takes quite a long time, compared with riffle or overhand shuffles, but allows other players to fully control cards which are on the table. The Mexican spiral shuffle was popular at the end of the 19th century in some areas of [[Mexico]] as a protection from gamblers and con men arriving from the United States.{{Citation needed|date=May 2023}}

===Team shuffle===
Especially useful for large decks, a shuffler may divide a deck into two or more smaller decks, and give the other portion(s) to (an)other shuffler(s), each to choose their own shuffling method(s). Smaller decks or portions of smaller decks may be traded around as shuffling continues, then the smaller decks are combined (and briefly shuffled) into the original large deck. This also prevents one shuffler having unfair control of the randomization.

===Cut===
{{main|Cut (cards)}}
Typically performed after a previous shuffling method, the cut is of simply taking a deck, dividing it into two portions of random size, and putting the previously lower portion on top of the previously higher portion. This is occasionally performed by a second shuffler, for additional assurance of randomization, and to prevent either the shuffler or an observer from knowing the top or bottom card.