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Note added 11/10/2010: Professor Ron Chen sent me another clock picture today of similar nature below:

The following diagram sent to me by my colleague, Jonathan Lee, at US Departemnt of Transportation, System Research Center , e ntitled "Clock for Engineers" is fun to decode (e.g., the cubic root of 1728 is 12). (By the way, try solving the problems first before looking at the answers provided by the readers below)

Some are not easy or obvious. I have not had time to decode them all. Readers are invited to participate. Here are few more easy ones:

3!=6,        6.99999 . . . =7,           ,  (5 2) = 10 etc.

Have fun!