Why division by zero is NOT infinity?

In mathematics we consider any number divide by zero is infinity. but why computer do not take that?

If computer wants to divide any number, actually computer substract the number till hit the zero.

9/3=3

9–3=6

6–3=3

3–3=0

If computer wants to do the multiplication do the addition.

16/4=4

4*4=16.

If we say

1/0=infinity

2/0=infinity

But 1 not equal to 2. it is not possible therefor we not consider in computer any number divide by zero is not infinity.

1/1=1

1/0.1=10

1/0.01=100

1/0.001=1000

When we trying to reach the zero the results should go upwards

1/0= infinity

-1/0= -infinity

The graph is not going to meet. there for this is undefinable. So we can say any number divide by zero is undefinable. Do not tell any number divided by zero is infinity it is undefinable.