Why is 1/0 undefined?
Division is the inverse of multiplication, therefore,
we know that 6/2 = 3 because 2 x 3 = 6
and that 18/3 = 6 because 3 x 6 = 18.
Now, if we try 1/0:
1/0 = ? if we can find a number to replace the question mark that solves this: 0 x ? = 1.
But there is no number we can use; no number multiplied by 0 will give us an answer of 1.
We get the same problem if we try 7/0 or -2/0 or 147/0 etc. [No number works.]
[Dividing 0 by 0 gives us a different problem; all numbers work.
We could argue that 0/0 = 1 because 0 x 1 = 0;
but then, by the same argument: 0/0 = 0 because 0 x 0 = 0
and 0/0 = 27 because 0 x 27 = 0
and 0/0 = -2 because 0 x -2 = 0.
So 0/0 is undefined because it has no single answer; every number works.]