How to get lost or stolen Android device IMEI number if the number is not recorded?

If you have linked your Android smartphone with your Google account, you can easily find the IMEI number of your device. I assume that every Android user has a Google account and signed in using the device.
Here is what you have to do-
1. Go to the link https://www.google.com/settings/dashboard?pli=1
2. Sign in to your Google account if not done already.
3. Click the arrow next to Android
4. You will get a list of Android devices linked to the Google account.
5. Look for your device and note down the IMEI number.

Another option is your bill.If you have purchased the phone you are having bill of the phone and bill also contains the IMEI no.Also if the bill is also misplaced you can check with the shop if he is having the bill because the shopkeeper also has to maintain the record.