REF-> Math Tricks Book

["Stephen E. Collins" <sec@BOOMBOX.MICRO.UMN.EDU>]

When I was young, I had a small book of math tricks.  It was full of
little short-cuts and other tidbits on doing math.  For example, the
trick of 9*n=xy where x+y=9 & x=n-1

Now that son is starting to enjoy math, I'd like to find this or
a similar book for him.  Unfortunately, I don't recall much
more about the book I had.  The local bookstore had nothing; I guess
learning basic math isn't popular any more :-(

I'd appreciate recommendations of titles.  Thanks!

Stephen E. Collins   <URL:http://www.micro.umn.edu/staff/sec>
University of Minnesota             sec@boombox.micro.umn.edu
Distributed Computing Services   (612) 625-1300 Fax: 625-6817

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