document.write( "Question 519368: Sorry i just sent an email and forgot the @ sign. My question is consider the set of 4 digit numbers 1000,1001.....9999. How many of these numbers has exactly three zeros behind it, and how many of the numbers has distinct digits i.e. No numbers are repeated. \n" ); document.write( "
Algebra.Com's Answer #345562 by Edwin McCravy(20086)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "My question is:\r\n" );
document.write( "Consider the set of 4 digit numbers 1000,1001.....9999. How many of these numbers has exactly three zeros behind it, \r\n" );
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document.write( "Just these 9\r\n" );
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document.write( "{1000,2000,3000,4000,5000,6000,7000,8000,9000}\r\n" );
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document.write( "and how many of the numbers has distinct digits i.e. No numbers are repeated.\r\n" );
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document.write( "Choose the first digit any of 9 ways (it can't be 0.\r\n" );
document.write( "Choose the second digit any of 9 ways, (it can be 0, but it can't be the one you selected for the first digit)\r\n" );
document.write( "Choose the third digit any of 8 ways, (it can't be either of the ones you selected for the first two digits)\r\n" );
document.write( "Choose the fourth digit any of 7 ways, (it can't be either of the ones you selected for the first three digits)\r\n" );
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document.write( "That's 9·9·8·7 = 4536\r\n" );
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document.write( "Edwin
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