0/0 is not defined.

Infact, any real number divided by 0 is indeterminate or not defined.

Eg. 2/0, 5/0, 6.5/0 etc. can not be defined.

To put it more lucidly consider

8/2=4 its because 2 multiplied by 4 is 8

20/4=5 its because 4 multiplied by 5 is 20

in general,  x/y = z means 'y' multiplied by 'z' gives 'x'

Now, if you write 6/0 then can you imagine a number which on multiplication with 0 gives 6 !!!!!!!!!!!!!!!!!!

Well, it can't be 2, it can't be 5, 4, 89, 1989, 100000000 or any other number thus, anything divided by 0 is not defined (indeterminate)

 

Further if we come to 0/0, then it is again 'not defined'.

But you may argue that 0/0=0 because 0 multiplied by 0 is 0, then on similar grounds i may argue that it can be 1, 2,3,5 or any other number, as anything multiplied by 0 is 0. Thus nothing definite is coming out. So such argument is absurd and is just a way of explaining or understanding a concept.

Finally, to conclude with we say 0/0 is not defined.