deepdream of
          a sidewalk
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Math and science::Analysis::Tao::06. Limits of sequences

Monotone bounded sequences converge

Increasing, decreasing and monotone

A sequence (an)n=0 is increasing if anan+1 for all nN and decreasing if an>an+1 for all nN. A sequence is monotone if it is either increasing or decreasing.

Monotone bounded sequences converge

If a sequence is [...] and [...], then it converges.

The easiest card ever. The proof is on the reverse; can you think of it? The proof is easy and obvious in retrospect, but it uses a property that I originally didn't consider using to solve the problem.