To find the percentage difference between 100 and 82, we first need to calculate the absolute difference between the two numbers.

The absolute difference between 100 and 82 is 18.

To calculate the percentage difference, we need to divide the absolute difference by the average of the two numbers (100 and 82), and then multiply by 100.

So, the average of 100 and 82 is (100+82)/2 = 91.

Now, we can calculate the percentage difference as follows:

Percentage Difference = (Absolute Difference / Average) x 100
               = (18 / 91) x 100
               = 19.78%

Therefore, the percentage difference between 100 and 82 is 19.78%.

This means that 82 is 19.78% less than 100.