In mathematics, division by zero is not defined, and this applies to the case of 6 divided by 0 as well. The reason for this is based on the basic properties of arithmetic and the way numbers are defined and used in mathematics.

To understand why division by zero is undefined, consider the following points:
- The definition of division: Division is an operation in arithmetic that involves dividing one number (the dividend) by another number (the divisor) to obtain a quotient. The division is defined as the inverse operation of multiplication, meaning that if a*b=c, then c/b=a. In other words, dividing a number by another means finding the number of times the divisor can be subtracted from the dividend.
- The concept of zero: Zero is a unique number in mathematics that represents the absence of a quantity or value. It is defined as the number that leaves any number unchanged when added, subtracted, or multiplied by it. For example, 0+5=5, 5-0=5, and 5*0=0.
- The result of division by zero: If we attempt to divide any number by zero, the result is undefined. This is because there is no number that can be multiplied by zero to yield the original number. In other words, dividing by zero does not make sense mathematically and cannot be represented by any real number.
To illustrate this point, consider the example of 6 divided by 0. We can write this as:
6/0 = ?
If we attempt to solve this equation by finding the number of times 0 can be subtracted from 6, we quickly run into a problem. No matter how many times we subtract 0 from 6, we will always get 6 as the result. In other words, 6/0 does not have a unique solution, as there is no number that can be multiplied by 0 to obtain 6.
Another way to think about this is to consider the limit of the quotient as the divisor approaches zero. If we plot the function y=6/x on a graph, we see that as x approaches zero from the positive side, the value of y becomes infinitely large (approaches positive infinity). Similarly, as x approaches zero from the negative side, the value of y becomes infinitely large in the negative direction (approaches negative infinity). This means that the function has no well-defined limit as x approaches zero, and the value of 6/0 is undefined.
In summary, division by zero is undefined in mathematics because it does not make sense mathematically and cannot be represented by any real number. The concept of zero as the absence of a quantity or value means that dividing by zero is equivalent to asking how many times a value can be subtracted from nothing, which is an undefined operation. While the result of dividing any number by zero is undefined, it is important to note that this does not mean that any number can be divided by any other number except zero. Dividing by a very small number can yield a very large result, but dividing by zero is not possible.