Shortcut to change percentages above 50% to odds?

RoyRoy Red Chipper Posts: 48 ✭✭
Working through Doug's Poker Work Book for Math Geeks and there have been a few exercises where I am calculating for odds that are greater than 1:1 (50%). Whereas I have a good grasp on how to convert back and forth between percentages lesser than 50% (e.g. 33% = 2:1) my brain seems to be running into a wall on anything that is higher than this 1:1 speed bump (i.e. .8:1). Maybe someone out there who is a lot better at math can provide a handy way to do this quickly?

Specific example would be from pg.88 having 72% equity and converting to x:1?

Comments

  • kageykagey Red Chipper, KINGOFTAGS Posts: 2,241 ✭✭✭✭✭
    edited September 2016
    Damn - good Q...
    there's a video, I think, where Doug or one of the coaches talks about figuring out this... I will try to look around and see if I can find it.

    But one of the quickest methods is just going to the nearest "whole percentage" that's easy for you to figure out... for example, for 72% equity - I'd round it up to 75% which is
    3 to 4 (¾ is 75%). If it was 83% - I'd go to 80 which is 4 to 5 (4/5 is 80%).

    I think I'm doing it right... lol!
    I'll try to dig up that video and you can view it for yourself...

    EDIT:
    check out "Bracketing" video
  • Matt BerkeyMatt Berkey Red Chipper, RCP Coach Posts: 278 ✭✭✭
    edited September 2016
    It's just the percentage divided by the difference of 100 over 1. So...
    72/28 = 2.57
    So it's 2.57 to 1.
  • EazzyEazzy Red Chipper Posts: 986 ✭✭✭✭
    edited September 2016
    .8:1 means you win 8 times and loose 1....so the total number of plays is 9

    so its 8/9 * 100 or 89% as a formula (i hate formulas but if one must)
    (times you win/(times you win+times you loose)) * 100

    going the other way its just 89% means you win 89 times out of 100 witch means you loose (100-89) 11 times....so itl's 88/11 which reduces down to 8/1 or 8 to 1


    Using Matt example (and he confused me a little)....
    2.57 to 1 means you win 2.57 for every 1 time you loose

    so it 2.57/(2.57+1) * 100 = 2.57/3.57 * 100 = 72%

    starting from 72% means you win 72 out of 100 or you loose 100-72 =28
    so its 72/28 which reduces down to 2.57 to 1
  • RoyRoy Red Chipper Posts: 48 ✭✭
    Ok, then what is the example trying to show?:

    /Users/roy/Desktop/Screen Shot 2016-09-26 at 12.43.26 PM.png
  • RoyRoy Red Chipper Posts: 48 ✭✭
    sorry, reposting pic:
  • RoyRoy Red Chipper Posts: 48 ✭✭
    Lets try this one more time:

    lj3kzjwjzya5.png
  • RoyRoy Red Chipper Posts: 48 ✭✭
  • RoyRoy Red Chipper Posts: 48 ✭✭
    Wouldnt it just be easier here (above) to say we are 2.7:1 for instead?

    It seems the 0.37 is calculated by dividing the remainder of of 100-73 (27) by the 73 and then putting this number :1.

    Definitely confuses me. It seems simpler to say that anything above 50% equity would just be for as opposed to a dog.....

    But please fill me in if Im going about this all wrong
  • EazzyEazzy Red Chipper Posts: 986 ✭✭✭✭
    I think the confusion you may be having is that odds can be quoted in two ways....

    3 to 1 or 4 for 1...these two are the same....

    In the to format you get your original bet back and 3 more...by in the for format you don't get your original bet back.

    If you ever looked at a crap table...some list the 66 (12) Payout as 30 for 1 while others list it at 29 to 1.....

    Honestly when calculating poker I only look at the %...and compare it to the % I need....I never bother with odds....

    Given the above example I would calculate the % total pot after I call 310....have to call 80, that about 27%.....have 32 outs (how we have 32 outs no idea but then I did not read the book assume 1 card to come) rule of 2 need 64% equityish....easy call...

    If I was then pressed to calculate the odds....(because of the bonus you get when you do this right)...I would just use the 27%.. (100-27/27) or a bit less then 3 to 1..but if you prefer....100/27 for a bit less then 4 for 1.....
  • Matt BerkeyMatt Berkey Red Chipper, RCP Coach Posts: 278 ✭✭✭
    edited September 2016
    This thread has derailed into a ton of flawed math. All of you are confusing odds and probabilities. Percentages are probability (a number between 0 and 1). This will hopefully help:

    http://www.quickanddirtytips.com/education/math/is-there-a-difference-between-odds-and-probability
  • RoyRoy Red Chipper Posts: 48 ✭✭
    Thank you Matt,

    I am comfortable with the content of the link that you posted. My question still remains though in regards to why @Doug Hull is presenting the equity of 73% (probability) as 0.37:1 (odds) vs simply stating 2.7:1 for.

    I now understand how to come up these numbers in both ways but it seems counterintuitive to be thinking in these <1:1 numbers when dealing specifically with odds. I would think that as soon as a specific situation's equity is above the 50% probability threshold it is easier to start saying X:1 for instead of <1:1.

    Should I comfortable with both?
  • SaintsTigersSaintsTigers Red Chipper Posts: 238 ✭✭
    I convert it to a close familiar fraction. Here you have 8:1. Off the top of my head I didn't know what % that is. But I do know that 4:1 is the same thing as 25% and the odds for 8:1 is twice as worse as that, or 25%.

    Not sure if that explanation makes sense. But this is what I did in my head: 4:1 is 25% so 8:1 is 12.5%
  • RoyRoy Red Chipper Posts: 48 ✭✭
    Uh oh,

    4:1 is not 25% but rather 3:1

    Same with 8:1

    Probably worth checking out the link that Matt posted above.
  • SaintsTigersSaintsTigers Red Chipper Posts: 238 ✭✭
    edited September 2016
    Touche. Misstatement on my part. of course I know that a 1 in 4 chance is a the same as a 25% chance while 4:1 against means you have a 20% chance of winning. In game I keep everything as ratios mostly.
  • Matt BerkeyMatt Berkey Red Chipper, RCP Coach Posts: 278 ✭✭✭
    edited September 2016
    Roy wrote: »
    Thank you Matt,

    I am comfortable with the content of the link that you posted. My question still remains though in regards to why @Doug Hull is presenting the equity of 73% (probability) as 0.37:1 (odds) vs simply stating 2.7:1 for.

    I now understand how to come up these numbers in both ways but it seems counterintuitive to be thinking in these <1:1 numbers when dealing specifically with odds. I would think that as soon as a specific situation's equity is above the 50% probability threshold it is easier to start saying X:1 for instead of <1:1.

    Should I comfortable with both?

    Because bookmaker odds are read as x to 1 against. Since we are examining the case of the favorite we instead look at the inverse odds which are 27/73 = .3698 thus .37 to 1, or in other words we'd have to Lay 2.7 to 1 in order to give our opponent the correct price-- which is simply a conversion to the dog's price (1/.37 in simplified fractional form or 73/27). Are you following how this applies?
  • RoyRoy Red Chipper Posts: 48 ✭✭
    Read it like a book. Thx a lot

Leave a Comment

BoldItalicStrikethroughOrdered listUnordered list
Emoji
Image
Align leftAlign centerAlign rightToggle HTML viewToggle full pageToggle lights
Drop image/file