Re: Cool math shortcuts
Simple one, but you can use the thinking to devise other tricks.
Divide any number by 9:
1/9=.1111_
2/9=.2222_
3/9=.3333_
...
9/9=.9999_=1(They are equivalent)
10/9=9/9+1/9=1.1111_
11/9=9/9+2/9...
...
Not sure how useful it is. My physics advisor is the U.S. physics olympiad coach and knows a ton of these tricks. I will ask him to recommend a book or something on this.
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