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 490 and 7 is 483 (490 - 7 = 483).

Next, we need to find the average of the two numbers. The average of 490 and 7 is (490 + 7) / 2 = 248.5.

Now, we can find the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 490 and 7 is (483 / 248.5) x 100 = 194.5%.

This means that the second number (7) is 194.5% less than the first number (490). Alternatively, we can say that the first number (490) is 194.5% more than the second number (7).