document.write( "Question 1065991: Call an integer dangerous if no two of its digits are equal and no digit is 2. Call an integer sexy if all its digits are odd. How many four-digit integers are either sexy or dangerous? \n" ); document.write( "
Algebra.Com's Answer #681164 by josmiceli(19441)![]() ![]() You can put this solution on YOUR website! The 1st digit must exclude 0 or 2, so \n" ); document.write( "there are 8 choices for the 1st digit \n" ); document.write( "--------------------------------- \n" ); document.write( "The 2nd 2nd digit excludes the 1st digit \n" ); document.write( "and 2, so there are 8 choices \n" ); document.write( "--------------------------- \n" ); document.write( "The 3rd digit excludes 1st and 2nd digits \n" ); document.write( "and 2, so there are 7 choices \n" ); document.write( "-------------------------- \n" ); document.write( "There are 6 choices for the 4th digit \n" ); document.write( "----------------------------------- \n" ); document.write( "There are \n" ); document.write( "-------------------------------------------- \n" ); document.write( "So there are no overlaps with sexy integers \n" ); document.write( "count the number of dangerous integers \n" ); document.write( "that have all odd digits \n" ); document.write( "------------------------------------------ \n" ); document.write( "5 choices for the 1st ( dangerous integer ) digit \n" ); document.write( "are odd \n" ); document.write( "------------------------------------------- \n" ); document.write( "4 choices for the 2nd digit are odd \n" ); document.write( "--------------------------------- \n" ); document.write( "3 choices the the 3rd are odd \n" ); document.write( "----------------------------- \n" ); document.write( "2 choices for the 4th are odd \n" ); document.write( "----------------------------- \n" ); document.write( "There are \n" ); document.write( "----------------------------- \n" ); document.write( " \n" ); document.write( "There are 2568 dangerous numbers that are NOT sexy \n" ); document.write( "--------------------------- \n" ); document.write( "There are \n" ); document.write( "------------------------------------------- \n" ); document.write( "There are \n" ); document.write( "that are EITHER sexy or dangerous \n" ); document.write( "-------------------------------------- \n" ); document.write( "Definitely get a 2nd opinion on this!!! \n" ); document.write( "I could easily be missing something\r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |