The mode is defined as the number that appears most frequently in a data set. If all the numbers in a given set are different, it means that no number repeats. In such a case, there is no mode, because no single number has the highest frequency of occurrence.
For example, consider the set of numbers: 1, 2, 3, 4, 5. Each number occurs exactly once, so there is no number that appears more than any other. Therefore, this set has no mode.
In summary, if all the numbers are different, the mode is undefined or can be said to be ‘no mode.’