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  • Karthik Rajagopalan thinks this is interesting:

To find developer options on 4.2 and above, go to Settings > About Phone (or About Tablet). Look for the list item Build Number, and press it repeatedly until you start seeing toasts indicating you are only a few steps away from being a developer. When you see the message “You are now a developer,” you can enable the developer options on the primary settings screen.

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Cover of Beginning Android Programming: Develop and Design

Note

Important for development - I guess it is 7 times click...