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How to Calculate Odds

If you are trying to win the lottery or a game of chance, knowing the odds of a winning combination will help you determine your success.


  • TIP: For example, to find the number of possible arrangements of a pick four lottery ticket you would find four factorial, or four times three times two times one, which is 24.
  • Step 1: Divide the product of the probabilities by the number of arrangements.
  • Step 2: Write the odds of an event occurring as a ratio of some number to one. Use your answer to decide if your odds are worth the risk, such as picking those winning numbers or rolling the right combination.
  • FACT: In 2002, Jack Whitaker of Scott Depot, West Virginia, became the biggest lottery winner in history after winning $315 million from a $1 lottery ticket.
  • Step 3: Find the number of different arrangements for the selections by finding the factorial of the number of selections.
  • Step 4: Multiply all the probabilities together, top numbers multiplied by top numbers and bottom numbers multiplied by bottom numbers. This will give you the probability of making selections in exact order.
  • TIP: For example, the first number selection on a "pick four" lottery ticket, with number options ranging from one to 99, has a probability of one out of 99.
  • Step 5: Determine the probability of each remaining selection. Remember -- for each selection there is one less choice.
  • TIP: For example, the second number selection on the lottery ticket has a probability of one out of 98.
  • Step 6: Determine the probability of the first selection.

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