document.write( "Question 935448: Five different digits 7 3 6 2 5 are given. Out of these digits, 4 digits numbers are formed. Find the no. of 4-digit numbers formed which have at least one digit repeated. \n" ); document.write( "
Algebra.Com's Answer #568691 by Edwin McCravy(20055)\"\" \"About 
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document.write( "First find the number of four-digit numbers.\r\n" );
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document.write( "5 ways to pick the 1st digit.\r\n" );
document.write( "5 ways to pick the 2nd digit.\r\n" );
document.write( "5 ways to pick the 3rd digit.\r\n" );
document.write( "5 ways to pick the 4th digit.\r\n" );
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document.write( "That's 5×5×5×5 = 54 = 625 four digit numbers altogether.\r\n" );
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document.write( "We need to subtract from that the number of four-digit numbers\r\n" );
document.write( "which have no digit repeated.\r\n" );
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document.write( "5 wasy to pick the 1st digit.\r\n" );
document.write( "4 ways remaining to pick the 2nd digit.\r\n" );
document.write( "3 ways remaining to pick the 3rd digit.\r\n" );
document.write( "2 ways rewmaining to pick the 4th digit.\r\n" );
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document.write( "That's 5×4×3×2 = 5! = 120 four digit numbers with no digits repeated.\r\n" );
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document.write( "Answer: 625-120 = 505.\r\n" );
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document.write( "Edwin
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