Dividing by zero

[Jenny A]

I like the sandwich idea. Why would you try to divide a sandwich between zero people and how would you know when you were through?

I see, but why is it ok to multiply by zero? I'm not being obtuse, I seriously don't know. lol

Multiplication is really just a kind of addition. When you multiply 4 x 5 you are saying add four 5s together: 5 + 5 + 5 +5 = 20.

Reverse the numbers to get 5 x 4 and you are saying add five to 4s together: 4 + 4 + 4+ 4 + 4 = 20.

Notice that regardless of the order of the numbers in the question, the answer is the same: 4 x 5 and 5 x 4 both equal 20.

Now try it with zero. When you multiply 0 x 4 you are saying add zero fours together. Well if you don't have any fours, what do you have? Nothing. Zero

Try it the other way: 4 x 0. Now you are saying add four zeros together: 0 + 0 + 0 + 0 = nothing, nada, zip. Zero.

The answer isn't undefined, it's zero.