O is for Odds



Oasis.  A reference to Aristocrat’s Oasis 360 Player Tracking software used in some casinos.
[ ARCHIVE: Aristocrat.com ]

OBBO. Acronym for dealer takes “Original and Busted Bets Only”.  If players are forced to play out hands before the dealer checks for blackjack then this is one of several rule options available.   Under OBBO rules, if the dealer ends up with a blackjack, the dealer takes any busted bets and one unit from each un-busted hand on the table. This is a very unfavorable rule for players. Players are at risk to lose additional bets from splitting. See OBO.  See ENHC.   See BB+1.  See No Hole Card Basic Strategy.
[ wizardofodds.com ]

object of the game. The object of the game of twenty-one, also known as blackjack,  is to beat the dealer.  This is accomplished by obtaining a hand that totals higher than that of the dealer, but not greater than 21.  It can also be accomplished by having the dealer bust or go over 21.  If the player busts before the dealer then the player automatically loses even if the dealer subsequently busts as well.  See Rules of the Game.

OBO. Acronym for dealer takes “Original Bets Only”.  If players are forced to play out hands before the dealer checks for blackjack then this is one of several rule options available.  OBO is the most favorable and typical of most USA casinos.  See OBBOSee ENHC. See BB+1.
[ wizardofodds.com ]

OBS. {BS} Acronym for Optimum Basic Strategy, a new basic strategy that can only be played with the Speed Count.  Coined by Dan Pronovost.

ochko. (очко) In Russia, the game of blackjack was called “21” or “ochko” (meaning ‘The Hole’).

Click Me!odds.  Chance can be expressed either as a probability or as odds.  Odds are defined as the probability that an event will occur divided by the probability that the event will not occur.  In blackjack analysis, we typically prefer the use of probabilities.  See probability. See dealer odds.
Odds Probability Calculator


  • Probability to odds:  Divide the probability by one minus that probability. 

    Example: If the probability is 10% or 0.10 , then the odds are 0.1/(1-0.1) =  0.1/0.9 = 1/9 or “1 to 9”.

  • Odds to probability: Divide the odds by one plus the odds. 

    Example: If the odds are “1 to 9” or 1/9 , then the probability is (1/9)/(1+(1/9)) = (1/9)/(10/9) = 1/10 = 0.10 or 10%

off-the-top. The first hand of a new deck or shoe immediately after the shuffle.

Ofton, Loudon. (aka David Drury and Loudon Often) A professional card counter and writer for Blackjack Apprenticeship.
[ blackjackapprenticeship.com ] [ blackjackapprenticeship.com ] [ PODCAST: Aug 6, 2020 ]

Ohio.  In 2016, Ohio had 5 casinos with over 250 blackjack tables.
[ qfit.com ]

Oklahoma.  In 2016, Oklahoma had 10 casinos with 111 blackjack tables.
[ qfit.com ]

Eddie OlsenOlsen, Eddie. (aka Edward Olsen) Co-author of the book Break the Dealer and original developer of the TARGET system.  Before publishing Blackjack Confidential magazine for 18 years, Olsen was a reporter, columnist and operations editor with The Philadelphia Inquirer for 33 years.  Olsen is also an avid artist.  The TARGET system is NOT recommended.  See Jerry Patterson.
[ ARCHIVE:  eddieolsenartworks.com ] [ ARCHIVE:  eddieolsenartworks.com/The_Artist.html ]

Olsen TruCount {PCS/L2}. (Eddie Olsen) (1991) An unbalanced card counting system developed by Eddie Olsen with original computer system analysis by Michael Dalton.

A 2 3 4 5 6 7 8 9 10
-1 1 1 1 2 1 * 0 * -1

* Red or Black 7s count 1
Red or Black 9s count -1

BC = .96 PE = .52  IC = .76

[ 10-12/91 Olsen Blackjack Confidential ] [ 91 Olsen The Olsen TruCount ]

*Omega II. {PCS/L2}. (Bryce Carlson) (1992) An advanced balanced point count system. See Canfield Master.

A 2 3 4 5 6 7 8 9 10
0 1 1 2 2 2 1 0 -1 -2

BC = .92 PE = .67 IC = .85

[ 93 Carlson Blackjack For Blood ] [ qfit.com ]

one2six. According to SG Gaming, “A secure and versatile continuous multi-deck shuffler“.  See shuffle machine.

One-Two Count. {TCS} (1968) An unbalanced ten-count system described in Jacques Noir’s Casino Holiday.  Notice the perfect insurance correlation.  See Archer System.
[ 78 Archer The Archer Method of Winning at 21 ]

A 2 3 4 5 6 7 8 9 10
1 1 1 1 1 1 1 1 1 -2

BC = .61 PE = .72 IC = 1.0

One Up Blackjack. (c2010) A blackjack variation that calls itself “The world’s easiest blackjack game“.  Both player and dealer start with a King of spades as the first card.  There are no face cards in the deck as all face cards have been removed.  Only Ace through Ten remain.  Blackjacks in spades pay 2 to 1.  Players may hit, stand, double after any two cards.  Other rules apply. (HA ~ 0.94%)
[ wizardofodds.com ]

one-way deck. According to Wikipedia, a one-way deck is a deck of playing cards where the back of the cards has a pattern which can be oriented to have a “top” and “bottom”. Magicians and card sharps can use the orientations of cards in one-way decks to encode information that allows them to perform card tricks

online blackjack.  Can you beat online blackjack?  Probably not! Live online dealers typically will only deal 50% of a shoe or less.  Other live dealer games might use a continuous shuffler.  Colin Jones, of Blackjack Apprenticeship analyzed some of these games.  His conclusion was, “Blackjack can be beaten! But you’re not going to make money playing online casinos from home. The online casino blackjack games are just designed to crush you.”  I agree, however, taking advantage of marketing promotions can be profitable 🙂
[ blackjackapprenticeship.com ]

Open 21 BlackjackOpen 21. (March 3, 2017)  A double exposure blackjack variation where a tie is a push and player blackjacks automatically pays 3 to 2.  A player 21 is also an automatic winner.  (HA ~ 0.51% to 0.96%) However, players are forced to make a side-bet, called Perfect 11, of half the wager.  (HA ~ 6.21%)
[ wizardofodds.com ]

OPP Card Counting System. {PCS} (2005) Carlos Zilzer. A simpler card counting system where the player only counts the number of low cards dealt per round and compares this with the number of hands played in the round. The rules of OPP are:

  • A hand with no low cards (2 – 6) has a value of -1
  • A hand with one low card has a value of 0
  • A hand with 2 low cards has a value of +1
  • A hand with 3 low cards has a value of +2 and so on
  • Split hands are considered new hands

[ ARCHIVE: blackjackforumonline.com ]

opposition betting. {CS}. This is a multi-deck betting strategy where the player waits for the count to turn down before raising a bet.  Originally intended as a way to cover a bet spread.
[ 83 Snyder Blackbelt in Blackjack 85 ]
[ 90 Patterson Blackjack: A Winner’s Handbook 103 ]
[ 90 Patterson Count Reversal Strategy WIN 62 ]

optimal betting theory.  See Kelly Criterion.

orange.  A reference to a $1000 chip. Sometimes yellow. Also referred to as a pumpkin.

Oregon.  In 2016, Oregon had 8 casinos with 73 blackjack tables.
[ qfit.com ]

Oregon Surveillance NetworkOregon Surveillance Network. (OSN) (c2002) aka Red Hand Oregon Surveillance Network. An information sharing and networking website administered by the Oregon Association of Indian Gaming commissions.  OSN is a collaboration of nine Oregon based casinos.  According to their web site, in 2017, they claimed to have a membership of over 1100, and their site is free!  OSN is not just in Oregon.  According to reports, casinos from Nevada to Florida use it too.  Casino personnel can search by eye, hair, skin color, height, weight, build, facial hair, alias names, etc.  See Griffin Investigations.
[ oregonsurveillancenetwork.com ] [ bjinsider.com ] [ oregon.gov ]

Oscar’s Grind. {PBS} The goal of this system is to win one betting unit for each series of bets. First bet is 1 unit. If lost the next bet is also 1 unit. After each successive loss the next bet is always the same size as the bet just lost. When a series is losing the proceeds of a won bet are used to increase the next bet by one unit. No bet should ever be larger than necessary to end a series with a profit of one unit. All progression type blackjack systems are not recommended.
[ 79 Ainslie How to Gamble in a Casino 74 ] [ 70 Wilson The Casino Gambler’s Guide ]

OSN. See Oregon Surveillance Network.

OSR. See Overall System Rating.

OU, OU13 or O/U. See Over/Under 13.

out shuffle. See perfect shuffle.  See in shuffle.
[ 03 Poolside The Poolside Report: Blackjack Ace Tracking ]

outfielder. A team player who is not seated.

Overall System Rating. (OSR) A combined rating which includes betting correlation, playing efficiency, and the insurance correlation.  As an example, the Hi-Lo card counting system has a rating of 96.53.  See SCORE.
[ ARCHIVE: bjmath.com 2011 Richard Reid ]

over betting.  Something you should never do… unless you don’t care about money.  See Kelly Criterion.  See Gambler’s Anonymous.


Over/Under 13. (OU, OU13 or O/U) An optional side bet first introduced in 1988 at Caesars Tahoe in Stateline, Nevada that allows the player to wager on his original 2 cards as to whether they will total over 13 or under 13. The developer, Ken Perrie, a Caesars pit boss, owns the rights to the design of the unique table layout used. Typical rules have been:

  • No requirement to play over/under.
  • Wager based on original two card hand.
  • Not to exceed wager on blackjack hand.
  • Even money pays on win.
  • Aces count as 1 only.
  • Face cards count as 10.
  • Must have wager on blackjack hand to make Over/Under 13 bet.
  • House wins any 2 card totals of exactly 13.

Over Under 13 Blackjack

Basic strategy for the over/under bet is to never take it. A modified counting system is required to take advantage of the excellent profit potential in this game. A typical card count that would be effective for detecting favorable opportunities for this bet is:

A 2 3 4 5 6 7 8 9 10
1 1 1 1 0 0 0 0 0 -1

BC = .59 PE = .47 IC = .85 <  Regular blackjack play only

As can be seen from the BC and PE above this count would be ineffective for regular blackjack play.  See Crush Count.

HA = +6.56% (over)
HA = +10.06% (under)

[ 89 Snyder The Over/Under Report ] [ 89 Snyder Inside the Over/Under BJF ] [ 12/89 Snyder The Over/Under Spreads BJF ] [ 12/89 Wong CBN ] [ 3/90 Snyder Over/Under Goes Over BJF ] [ 3/90 Smallwood Crushing the O/U Bet BJM 8 ] [ 9/90 Snyder Over/Under Update BJF ] [ 90 Chambliss Fundamentals of Blackjack 67 ] [ 7/91 Olsen Ken Perrie – An Innovator on the… BJC ] [ 9/92 Schlesinger Lost in the Maze of New Rules BJF ] [ ARCHIVE: blackjackforumonline.com  ] [ qfit.com ] [ 888casino.com ] [ 888casino.com ] [ 888casino.com ]

Owen, Bert K. See entry under John Imming’s Multiparameter Blackjack Engine.

Owens, Griffith K. See Lawrence Revere.


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