To find the percentage difference between two numbers, we first need to find the absolute difference between them. In this case, the absolute difference between 57 and 100 is 43 (100 - 57 = 43).

Next, we need to find the average of the two numbers. The average of 57 and 100 is (57 + 100) / 2 = 78.5.

Now, we can find the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 57 and 100 is (43 / 78.5) x 100 = 54.78%.

This means that 57 is 54.78% less than 100, or that 100 is 54.78% more than 57.