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 210 and 247 is 37.

Next, we need to find the average of the two numbers. The average of 210 and 247 is (210+247)/2 = 228.5.

Now, we can find the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 210 and 247 is (37/228.5) x 100 = 16.17%.

Therefore, the percentage difference between 210 and 247 is 16.17%. This means that the second number (247) is 16.17% greater than the first number (210).