The meaning of the +9 symbol in betting varies from sport to sport. But, broadly speaking, it can be equated to the ‘match odds’ or ‘betting exchange rate’ in that it reflects the amount you need to bet in order to win your stake (plus your choice of margin).

The concept of ‘match odds’ was first introduced to the world during the early hours of September 09, 1928, when bookmaker Edward Lowth (the ‘Parley’ in Parley For All Sports) set up a wager between two men, each wagering £9 on the results of an exhibition football match between the USA and Canada. The men agreed to arbitration based on the handicap system used in horse racing, with the Canadian having to wear a tiepin, badge or something similar on his chest to identify himself as the underdog.

The first recorded instance of the +9 symbol in bookmaking is in respect of a horse race in Newmarket in 1929. At that time, bookmakers would often abbreviate the odds to just the numeric value 9 because there were no ‘computers’ or digital calculators which could quickly give odds in arithmetical operations. The abbreviation survived into the digital age and is still used today.

Here is a timeline of the evolution of the +9 symbol from the ancient times of ancient Greece through to the modern era:

## The Evolution Of The +9 Symbol

The +9 symbol represents an important development in the field of betting because it offers a clear and simple way of expressing the betting odds for a variety of sports. Prior to its advent, people had to resort to the use of charts and graphs to work out what the betting odds were in a given situation. This often led to errors and inaccuracies because it was difficult to keep track of the numerous permutations and combinations that could arise when calculating the odds of, say, a tennis match.

By way of example, let’s examine how to work out the odds of a tennis match between Roger Federer and Rafael Nadal.

To start with, we’ll need to consider our stake, along with the amount we want to wager on the basis of our assessment of Nadal’s chances of winning. We’ll assume the latter to be ‘+’ for the purpose of this example. So, our stake is £100, and we have made a wager of £9 on Nadal winning the match. If we were to place a ‘0′ wager, then we would risk £0 on Nadal winning the match. (The odds of a Nadal win are 11/11 or 1.11, so placing a 0 wager essentially means we are wagering on the outsider, Andre Agassi).

Similarly, if we were to place a ‘–’ wager then we would risk losing our entire stake. In this instance, the odds of Nadal winning are 16/11 or 1.6, which is why we are effectively betting on Nadal to lose.

In order to work out the odds of Roger Federer winning the match, we will need to do the following:

- Add up all the winning bets on Nadal (1.6 x £9 = £16.80)
- Subtract all the losing bets on Nadal (1.6 x £0 = £0)
- Add up all the winning bets on Federer (1.11 x £9 = £10.91)
- Subtract all the losing bets on Federer (1.11 x £0 = £0)
- Add up all the winning bets on Nadal
- Subtract all the losing bets on Nadal
- Add up all the winning bets on Federer
- Subtract all the losing bets on Federer
- Choose which result you want to bet on (2 possible outcomes)
- Work out your stake (100 x 2 = £200)
- Choose your wager (either + or –)
- Work out your winnings (plus your stake) if Nadal wins
- Work out your winnings (plus your stake) if Federer wins

As you can see, there are four possible permutations for this tennis match—each one offering a different payoff. This makes it relatively easy to keep track of the numerous permutations and combinations which could arise when working out the odds of any given event.

However, if you were to use a traditional odds calc machine, which was once the only way to work out the odds of a sporting event, then you would find it very difficult to keep track of all the various permutations and combinations. This is where the +9 symbol comes in.

## The Evolution Of The Modern Era

Thanks to the development of computer software designed to work out the probabilities of sporting events, the world of sports betting underwent a transformation in the late 20th century. With the advent of the internet and online databases, it became possible to keep track of all relevant data in an instant, which is why we see such a huge increase in the use of such tools. (These days, the data needed to work out the odds of a sporting event can be found online in seconds, rather than by going down to the bookmakers and getting the totals from the till. This is a luxury offered only by big-name bookmakers who have the resources to maintain large online databases.)

One of the first events successfully codified using such tools was the Grand Slam tournament, which is why you often see odds for these tournaments expressed in the form of a decimal. For example, the French Open 2019 odds are 33/1 (1.33 or so), which can be broken down as 33 for the French Open, 1 for the first round, 1 for the second round and 1/1 for the third round. (This particular example of odds is commonly abbreviated to ‘33/1′, which is why we saw this notation used for the French Open later on in this timeline).

## +9 Means…

In summary, the +9 symbol represents a simple way of expressing sporting event odds in a concise and accurate manner. But, as we’ve seen, it only has one definition in betting, namely the ‘match odds’. This is how it should be for a mathematical symbol, as it represents a clear and concise way of denoting a numerical value (1.33 or 1.6) which can be used in a variety of sports situations. This is reflected in the I.O.U. code for casinos, which is used worldwide in the horse racing and greyhound racing sectors. (Integrated Offering Underling; this is the official designation for a Contract-for-Difference betting product offered by a bookmaker).

In addition to defining the odds of a sporting event, the +9 symbol can also be used to calculate the amount you need to bet in order to win your stake (plus your chosen margin. So, if you’re betting £10 and you want to win £15, then you need to bet £9. This is commonly abbreviated to ‘+9′, and you might see this symbol used in the industry to denote ‘plus-or-minus’ odds, although these days, bookmakers will usually just use parentheses to denote such numbers.)

The +9 symbol will continue to evolve with the times, and it is likely that we will soon see additional uses for it, particularly in areas where keeping track of all the odds in a given situation can be difficult. (For example, in online poker where there are often many thousands of players at any one time, and the cards are dealt in a different manner depending on whether the customer is betting on poker or casino games). But for the time being, its primary use is unquestionably as a concise and accurate way of expressing sporting event odds. (The world of sports betting continues to operate largely under the radar of the traditional bookmaking world, and many people in the industry still prefer to use the +9 symbol to keep track of their wagers rather than switch to more modern methods of recording sporting events).