Like in all the gambling games the casinos try to show everything in a light that let the player to think he could win big amounts of money in any game anytime and that they are participating in a fair game, or close to fair. In games like craps, the odds are always stacked against us, but most people don't know where.
There is a bet that has no house edge and this is the free odds bet. Taking odds you are increasing your bet in a way that increases your payout if you win. When you take odds, you are betting money in addition to your original bet, once a point has been set. The odds bet wins if your flat bet wins, and loses if your flat bet loses. While your Pass-line bet pays even money if you win, an odds bet pays out the exact odds, or probability of rolling the point. Since the odds pay off better than the initial bet, you should always maximize your odds bet.
When you bet a Pass line bet the natural house edge is around 1.42%. When you back the bet with free odds, the overall house could be said to drop. The greater the proportion of your bet that is on free odds, the lower the edge will get. This is why most casinos limit the amount you can place on free odds. When the table has a 5x showing, you can place five times as much on your odds as you put down as the Pass line bet. If you bet a $10 Pass line bet, you could put as much as $50 down on free odds.
To get a better idea about where it all comes from, have a look at the chart below.
This details how common each total is from a combination of two dice. The very familiar number 7 is the most popular, as there are more ways to make a seven out of two dice than any other number. That means that on any given roll, there is a better chance a seven will come up before any other number. The odds of rolling a 3 can be found by stating the number of possible ways to roll a 3, compared to the number of ways to roll something that's not a 3. This turns out to be 33 to 3, or 11 to 1 that a 3 will be rolled.
An important use of this information when it comes to craps is our ability to determine the odds of one number being rolled before another. The odds of a 4 being rolled before a 7 can be seen by comparing the number of ways to roll a 4 (which is 3) with the number of ways to roll a 7 (which is 6). The odds against rolling a 4 before a 7 are 6 to 3, or 2 to 1.
Working this out we find that it's best to bet on the 6 or 8 coming up before a seven, as it makes for the best craps odds available.