Question

when we divide a number by zero how can it will be not define

Answer 1

it is not possible to divide any number by zero because if there is zero in the denominator then it cannot divide any other number for example if you want to make first floor without making the ground floor or you try to remove the ground floor that is impossible or undefined first floor cannot be made until we make the ground floor first

Answer 2

try to divide any no by 0.
take 1/0
Now whatever the quotient u will take , the remainder will always be 1 & the quotient will reach to infinity but remainder will still be there .

so it can't be defined