Which type of loop is best if you do not know how many times you need the loop to run?

You are to write a series of steps that anyone could follow to solve the following three problems: 1. even odd a. assume that someone tells you a number (an integer number) b. you hear the number and respond with the word even or odd 2. average a. assume that someone tells you between 3 and 5 numeric values. b. you hear the numbers and respond with the average is some number 3. dog or cat a. explain to a child the differences between a dog and a cat. b. your explanation could be used by a child or anyone to distinguish the difference between a dog and a cat