23. Given two arbitrary natural numbers; determine the probability that their product will be an even number; that it will be an odd number. (Definition of probability see question 375.)

Determine the probability that their product will be an even number; that it will be an odd number.
23. There are four equally possible cases: $and and, and not$, and and, not and; in three of them the product is an even number, in one only an odd number. Therefore, the corresponding probabilities will be: $\frac{3}{4}, \frac{1}{4}$.