A Different Sort of Arithmetic

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There's construction going on in my university, and I found some fascinating figures written on one of the walls (presumably by the construction workers). It looked like someone had gone to a lot of trouble to prove that 7*13=28. Actually, assuming you can play mix 'n' match with units and tens, it's quite convincing! But it's driving me nuts. Can someone look at the attatched thumbnail and tell me what's really going on?

EDIT: the "figure 1" "figure 2" "figure 3" are my own additions.
 

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7 * 13 feet is approximately 28 meters.

- Warren
 
This is a parody of a video circulating around the internet that involves some “funny math”:

http://video.google.com/videoplay?docid=4241480654150026320&q=funny+math&hl=en
 
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chroot said:
7 * 13 feet is approximately 28 meters.

- Warren

Thanks! (I will now be able to walk into the lobby without fearing for my life...)
 
3.14159 said:
This is a parody of a video circulating around the internet that involves some “funny math”:

http://video.google.com/videoplay?docid=4241480654150026320&q=funny+math&hl=en

Yeah, that's exactly what I thought had been done!
 
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