Four Twos PuzzleDate: 05/31/99 at 23:56:25 From: Jonathan Ma Subject: Using 4 twos to get special numbers How can I get 15, 17, 19 and 21 using 4 twos? I've tried to use exponents, radicals, and the order of operations. Thank you for your time and help. Date: 06/02/99 at 02:31:05 From: Doctor Floor Subject: Re: Using 4 twos to get special numbers Hi, Jonathan, Thanks for your question! I found three of your numbers, using the trick of writing .2 for 0.2: 15 = ( 2 + 2/2)/.2 19 = (2*2 - .2)/.2 21 = (2*2 + .2)/.2 Here's a weird possibility for 17: 17 = 22 - sqrt(.2^(-2)) Here, .2^(-2) is .2 to the power -2, which equals 25. Good luck! Best regards, - Doctor Floor, The Math Forum http://mathforum.org/dr.math/ |
Search the Dr. Math Library: |
[Privacy Policy] [Terms of Use]
Ask Dr. Math^{TM}
© 1994-2015 The Math Forum
http://mathforum.org/dr.math/