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Find the number of 4-letters words possible by taking 4 letters from the word \"INKLING\".
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document.write( "Case 1: No repeated letters from these 5: {I,N,K,L,G}\r\n" );
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document.write( "Choose the 1st letter 5 ways.\r\n" );
document.write( "Choose the 2nd letter 4 ways.\r\n" );
document.write( "Choose the 3rd letter 3 ways.\r\n" );
document.write( "Choose the 4th letter 2 ways.\r\n" );
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document.write( "That's 5P4 = 5*4*3*2 = 120 ways for case 1.\r\n" );
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document.write( "Case 2: There are 2 I's but not 2 N's\r\n" );
document.write( "Choose the 2 positions for the I's 4C2 = 6 ways\r\n" );
document.write( "Choose the letter for the leftmost unchosen position 4 ways, from {N,K,L,G}\r\n" );
document.write( "Choose the letter for the rightmost unchosen letter 3 ways.\r\n" );
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document.write( "That's 6*4*3 = 72 ways for case 2.\r\n" );
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document.write( "Case 3: There are 2 N's but not 2 I's\r\n" );
document.write( "Same as Case 2.\r\n" );
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document.write( "That's also 72 ways for case 3.\r\n" );
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document.write( "Case 4. 2 N's and 2 I's\r\n" );
document.write( "Choose the positions for the N's 4C2 = 6 ways.\r\n" );
document.write( "Put I's in the remaining 2 places only 1 way.\r\n" );
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document.write( "That's 6*1 = 6 ways for case 4\r\n" );
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document.write( "Grand total: 120+72+72+6 = 270\r\n" );
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document.write( "Answer: Choice (A)270\r\n" );
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document.write( "Edwin \n" );
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