Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
NCTM or The Math Forum.



Quick Solution to Puzzle?
Posted:
Aug 7, 2013 8:12 AM


Hello, all. I came across this puzzle in an old computer reference book in a chapter dealing with efficient programming techniques:
Find a 7digit phone number (I told you the book was old) such that when the first three digits are subtracted from the last four and the result squared you obtain the original 7digit number. The answer is 1201216. I'm uncertain if there are any other integer solutions. The problem can be reduced to a quadratic in two unknowns and numbers substituted until the answer is obtained. Does anyone know of an alternative, relatively fast (pencil & paper) solution? Thanks for your time and comment. Sincerely,  J. B. Wood email: arl_123234@hotmail.com



