xkcd #3138: Dimensional Lumber Tape Measure
Title text:
A person with two watches is never sure what time it is, especially if I got them one of the watches.
Transcript:
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Source: https://xkcd.com/3138/
The carpenter or woodworker cares about how big the board is. The sawyer cares about how much of the tree it took to make that board. The lumber yard has to make those two ends meet at a price point.