Hi, Lisa here and I'm going to show you how to find your serial number on a Mac. So, the first way you can go to the apple, click on it and then click on "About This Mac." Where it says version and then your version of your software, you can actually click on that and it will show you the build number of your computer and if you click again, it will show you the serial number.
So, that's a really quick way to find that number. Then, you can also find it by going to "More Info" an opening that and then you'll see the serial number down here on the 4th line of information and even further you can go to "System Report" and on the very first page of hardware, you'll see it there at the second to last line. Finally, if your computer wont turn on, the serial number is on most models on the bottom of the computer. And that's it. That's how you find the serial number on your Mac.