document.write( "Question 1011744: Let X be a four-digit positive integer such that the unit digit of X is prime and the product of all digits of X is also prime. How many such integers are possible?
\n" ); document.write( "(1) 4 (2) 8 (3) 12 (4) 24 (5) None of the above \n" ); document.write( "
Algebra.Com's Answer #627501 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Since the units digit is prime, all the other digits must be 1s,\r\n" );
document.write( "because if any of them weren't 1 the product would not be prime. \r\n" );
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document.write( "The units digit can only be 2,3,5, or 7, since they are the only\r\n" );
document.write( "digits that are prime,  so there are four,\r\n" );
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document.write( "1112, 1113, 1115, 1117.  \r\n" );
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document.write( "Edwin
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