document.write( "Question 722997: Identify the number that satisfies all three of the following conditions:
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document.write( " it is a composite between 62 and 72;
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document.write( " the sum of the digits is a prime number; and
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document.write( " it has more than four factors. \n" );
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Algebra.Com's Answer #442980 by josgarithmetic(39618)![]() ![]() ![]() You can put this solution on YOUR website! The range of possibilities is very limited. Some or the possibilities to first consider could be from the set of {62,63,64,65,66,67,68,69,70,71,72}. It is a COMPOSITE number, so eliminate the primes. Look in {62,63,64,65,66,68,69,70,72}. \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Sum of the digits is prime! This cuts down the possibilities to {65,70}. 6+5=11 prime, and 7+0=7 prime. \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "FOUR FACTORS? Cannot be 65 because this one only has 5 and 13 as its factors. The number must be 70 to satisfy all three conditions. 70=7*10 and 70=35*2, but the condition is still not a fit because also 70=14*5. If you were to rely on a very simple elementary way of thinking, you could choose 65 because in the very elementary sense, the factors of 65 are: 1, 5, 13, and 65.\r \n" ); document.write( "\n" ); document.write( "ANSWER: Must be 65. \n" ); document.write( " |