Google Keyboard number row
Go to settings, Security and then check Unknown sources. You have to remove any previous versions of Google keyboard so go to Settings, Application Manager and go over to Google Keyboard. If you are using a Nexus device then you will need root privileges. Download the modified Google keyboard from here: http://forum.xda-developers.com/showthread.php?t=2657791 After installation click open to enter settings or open the app from the app drawer. Configure the keyboard then set it as your default in settings.

Link:
http://www.techaudible.org/how-to-add-dedicated-numbers-row-to-native-google-keyboard/