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 73 and 56 is 17.

Next, we need to find the average of the two numbers. The average of 73 and 56 is (73+56)/2 = 64.5.

Now, we can find the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 73 and 56 is (17/64.5) x 100 = 26.36%.

Therefore, the percentage difference between 73 and 56 is 26.36%. This means that 73 is 26.36% greater than 56.