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 64 and 125 is 61 (125 - 64 = 61).

Next, we need to find the average of the two numbers. The average of 64 and 125 is (64 + 125) / 2 = 94.5.

Now, we can find the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 64 and 125 is (61 / 94.5) x 100 = 64.55%.

This means that the second number (125) is 64.55% greater than the first number (64).