When betting on the favorite, simply divide the negative moneyline by 100 to get a decimal. If you were planning to bet on the Celtics in the above example, this would give you 2.40 (ignore the negative). Now all you have to do is divide your stake by that number in order to see what your potential payouts would be. Let's say you wanted to stake $650. When you divide that number by 2.40, you'd see that your potential payout is $270.83.
Many people will say that the odds on a spread bet are even, paying 1:1. But this is not true. The actual odds are 0.90:1. For every dollar bet, you can win 90 cents. When checking out the spread, you’ll usually see a number listed next to each spread. That number, which is your stake, is posted as -110. This number tells you how much you have to bet to win $100. If you put $110 on either team, you stand to win $100. If you bet $11.00, you can win $10.00. Every NFL point spread works this way.

In this example the Jets are listed as four-point favorites (-4) over the Bills and the 49ers are three-point underdogs (+3) against the Seahawks. So, if you bet $110 on the favored Jets, they must defeat the Bills by more than four points in order to win $100. If you bet $110 on the underdog 49ers you will win $100 if they win outright or lose by less than the three-point spread. If the final score happens to end up exactly on the number it's a tie, or 'push,' and you get your money back.
The point spread, which is sometimes referred to as the “handicap”, is the number of points taken from the favorite, or given to the underdog, in order to open up the chances of either team winning the wager evenly. In most games, there’s usually a team that is more likely to win, based on a number of statistical factors. If the only kind of wager available was on who would win between a very strong team and a poor team, it wouldn’t be all that exciting. The point spread was designed to make betting much more interesting, since it allows a bet on the losing team to win you money. How? Let’s break down an example: