to add a bit more to sean.1986
it come down to decimal places and zeros, 1 million has 6 zeros, and a total of 7 digits ie 1000000. when you are dealing with very large numbers it is easy to add or loose digit, so if you place a decimal point after the first digit, in this case 1, then count the remaining digits, in this case 6, it is then written in scientific notation as
The reverse of this happens on the other side of the decimal point, a millimeter is 1/1000 of a meter or 0.001m or
When multiplying you add the powers, and multiply the bases
when dividing you subtract the powers and divide the bases
You can then adjust the decimal place ant the notation to suit as sean.1986 has done in the answers that he has provided
a final thing to watch for, sometimes the letter E will be substituted for x10, mainly on calculators, the trap as I found is that I thought E is the same as e, which it isn't. e is what is called a natural log.
I hope some of this makes sense