Please explain how to do #3

Leo is going to use a random number generator 4 0 0 400 times. each time he uses it, he will get a 1 , 2 , 3 , 4 , 1,2,3,4, or 5 5. what is the best prediction for the number of times that leo will get an odd number?

Define multiplicative inverse. give an example of a number and its multiplicative inverse.

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.