Mathematically, 1 + 1 = 1 is impossible. However, in the real world, if you have two piles of stuff and you put them together you have one pile. In Boolean Algebra, there ar
…e only two numbers, one and zero. These numbers stand for true and false, respectively. In Boolean Algebra "1+1" is not "1 plus 1" but rather "1 or 1", or "true or true". Since both are true the answer is true, so in Boolean algebra, 1+1=1. Basically what these wannabe maths professors are getting at is 1+1= never really 1 but they just want to sound clever. Since it's in the Percentages category - say you have two machines in the factory to produce a product. The capacity of the factory is 100%, which would happen only if both machines were running at 100% capacity. This doesn't really make 1+1=1, because the units (rates of speed) are not equal. For example, if you made up some kind of unit which is 13 inches long, where 1 foot + 1 inch = 1 of the new unit. (MORE) 
