If Mr. Flynn is 90 centimeters plus half his height, how tall is he?

Why this works

This riddle plays with the relationship between Mr. Flynn's height and a simple mathematical equation. When it states that Mr. Flynn is "90 centimeters plus half his height," we can set up an equation where his height (let's call it H) is equal to 90 centimeters plus half of H (which is H/2). So, if we express this mathematically: H = 90 + (H/2). By multiplying everything by 2 to eliminate the fraction, we get 2H = 180 + H. Subtracting H from both sides gives us H = 180 centimeters. Thus, Mr. Flynn's height is indeed 180 centimeters!