In this Question Line video, Jason answers the following question regarding flatness and Rule #1: 

I recently completed the GD&T Basics course and passed the exam. There is one question related to flatness that I missed that I’d like to understand better.

The student referred to the following exam question: 

 

Jason shows how to calculate the amount of flatness for the top surface based on the size tolerances and Rule #1. He notes that the top surface is only required to be flat because of Rule #1, and the flatness of the bottom surface has no effect on how much flatness the top surface is allowed. 

 

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