Write down the number of ways in which a selected number could be chosen. For example, if you must choose one number, you would write down 1. If you can choose two numbers, you would write down 2.
Write a fraction bar underneath or to the right of the number that you wrote in Step 1.
Write the number of possible outcomes underneath or to the right of the fraction bar. For example, consider that you are playing a game in which there is a "lucky" number between 1 and 50. You can choose five numbers as your guesses. Therefore, your probability fraction would look like this: 5/50.
Simplify the fraction if possible. In this case, you can divide 5 and 50 by the number 5, which gives you a simplified fraction of 1/10. This means that the probability of you choosing the correct number is one in 10.