document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1206462>Question 1206462</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Grandpa and his grandson Gary both had their birthday yesterday. Today, grandpa's age in years is an even number and 15 times that of Gary. In 4 years time Grandpa's age in years will be the square of Gary's age in years. How many years older than Gary is grandpa today? </SPAN>\n" );
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document.write( "Grandpa's age is an even number that is 15 times his grandson's age.  15 times a whole number being an even number means that whole number is even.  So there are only a few reasonable possibilities to check.<br><BR>\n" );
document.write( "grandson 2, grandpa 30: 28 years is too little length for 2 generations; and 30+4=34 is not a perfect square.<br><BR>\n" );
document.write( "grandson 4, grandpa 60: 56 years is a reasonable length for 2 generations; and 60+4 is a perfect square.<br><BR>\n" );
document.write( "grandson 6, grandpa 90: 84 years is PROBABLY too long for 2 generations; and 90+4 is not a perfect square.<br><BR>\n" );
document.write( "So Grandpa is 60 and his grandson is 4; the difference in their ages is 56 years.<br><BR>\n" );
document.write( "ANSWER: 56<br><BR>\n" );
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