What is the probability of rolling a number less than 5 or a odd number?

You didn't mention whether this was one die or two dice. If one die, then the possibilites are 1 and 3, so this is 2 outcomes out of 6 or 1/3. Probability can stated as 0.33 or 33%. If two die, there is 2 possibilities: (1,2) and (2,1) out of 36 outcomes which is 1/18 = 0.055. Probability can be stated as 0.055 or 5.5%.