Theorem: 1$ = 1c.
Proof:
And another that gives you a sense of money disappearing.

1$ = 100c
= (10c)^2
= (0.1$)^2
= 0.01$
= 1c

Here $ means dollars and c means cents. This one is scary in that I have seen PhD’s in math who were unable to see what was wrong with this one. Actually I am crossposting this to sci.physics because I think that the latter makes a very nice introduction to the importance of keeping track of your dimensions.

This joke was submitted by Harry.