document.write( "Question 1100936: The digits 0,1,2,3,4 are to be used in a four digit ID card. How many different cards are possible if repetitions are permitted?\r
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Algebra.Com's Answer #715494 by ikleyn(52830) $\"\"$ $\"About$

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document.write( "If repetitions are permitted, then\r\n" );
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document.write( "    - you can put any of the given  5  digits to the 1-st position (5 opportunities);\r\n" );
document.write( "    - you can put any of the given  5  digits to the 2-nd position (5 opportunities);\r\n" );
document.write( "    - you can put any of the given  5  digits to the 3-rd position (5 opportunities);\r\n" );
document.write( "    - you can put any of the given  5  digits to the 4-th position (5 opportunities).\r\n" );
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document.write( "In all, you have  = 625 different card ID numbers under this scenario.\r\n" );
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document.write( "If repetitions are not permitted, then another logic works:\r\n" );
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document.write( "    - you can put any of the given     5 digits to the 1-st position (5 opportunities);\r\n" );
document.write( "    - you can put any of the remained  4 digits to the 2-nd position (4 opportunities);\r\n" );
document.write( "    - you can put any of the remained  3 digits to the 3-rd position (3 opportunities);\r\n" );
document.write( "    - you can put any of the remained  2 digits to the 4-th position (2 opportunities).\r\n" );
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document.write( "In all, you have 5*4*3*2 = 120 different card ID numbers under this scenario.\r\n" );
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