document.write( "Question 1195504: How many 5-digit numbers can be formed using numbers 0, 1, 2, …9, such that repetition is NOT allowed \n" ); document.write( "

Algebra.Com's Answer #828008 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "How many 5-digit numbers can be formed using numbers 0, 1, 2, …9, such that repetition is NOT allowed
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document.write( "Any of 9 digits at the most-left position,  giving 9 possible options;\r\n" );
document.write( "       (any of ten digits, except of 0);\r\n" );
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document.write( "Any of remaining 10-1 = 9 digits at the next position,  giving 9 possible options;\r\n" );
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document.write( "Any of remaining  9-1 = 8 digits at the next position,  giving 8 possible options;\r\n" );
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document.write( "Any of remaining  8-1 = 7 digits at the next position,  giving 7 possible options;\r\n" );
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document.write( "Any of remaining  7-1 = 6 digits at the next position,  giving 6 possible options.\r\n" );
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document.write( "Thus in total, there are  9*9*8*7*6 = 27216 different 5-digit numbers as described.\r\n" );
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\n" ); document.write( "\n" ); document.write( "The lesson to learn from my solution is that a leading digit can not be 0 (zero).\r
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