document.write( "Question 706693: How many seven-digit telephone numbers are there that begin with 347 and contain at least one 0 and at least one 1 ? \n" ); document.write( "
Algebra.Com's Answer #435365 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Here is a much easier way to do it.\r\n" );
document.write( "They all start with 347, so we need only consider the\r\n" );
document.write( "4-digit numbers following that.\r\n" );
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document.write( "There are 104 or 10000 4 digit numbers.\r\n" );
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document.write( "From that we must subtract those that are \"zero-less OR one-less\"\r\n" );
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document.write( "N(zero-less OR one-less) = N(zero-less) + N(one-less) - N(zero-less AND one-less)\r\n" );
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document.write( "                       =       94    +     94     -         84\r\n" );
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document.write( "                       =     6561    +   6561     -       4096 \r\n" );
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document.write( "                       =     9026 \r\n" );
document.write( "Subtract from 10000, \r\n" );
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document.write( "              10000 - 9026 = 974\r\n" );
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document.write( "Edwin
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