You want the while loop to keep looping if the correct guess was not given, right? In this case, this means the person has answered the question (in the 2 print statements) with an answer other than "y" (with "y" standing for "yes"). What condition would you put in the while loop to keep it looping if $ans \ne$ "y"?

The code works as follows: we start our guess range to be between low and high which is between 1 and 100. We always guess a number that is midway between the numbers in low and high. As the program begins, this will be 50, which is $(100+1)/2$ (the math.floor function is used to drop any decimal point).

The program works by reassiging either low or high to its last guess and deriving its next guess from "guess=$\frac{low+high}{2}$." For example, if its first guess of 50 is "too low," it'll assign varible low to 50 (high is still 100). The next guess will be $\frac{50+100}{2}=75$, etc.