Place a decimal point between the first two digits (4 and 8). Erase the commas and the 0s. So you'll have 4.86 left over after you've done that erasing.
Now ask yourself: "how many places to the right must I move the decimal to get 4.86 to turn back to 48,600,000?"
That would be 7 places to the right. That 7 is the exponent over the 10
Therefore, the answer is 4.86 * 10^7
This number is 48.6 million