Hi, in my physics book (serway) they say "dimensions can be treated as algebraic quantities" but I don't understand this very well. If I sum meters I get meters, if I multiply meters I think I get meters^2 because the area of a rectangle is b.h. But if, for instance, I multiply seconds.seconds I don't uderstand why I get sec^2. Algebraically x.x = x^2 but x represent a a number not time, weight, etc. I see it like 3 apples x 2 apples = 6 apples^2. Probably I'm getting this wrong, Could you help me to understand this right please? As always, excuse me if my english isn't very clear.