document.write( "Question 535615: Please help me to solve this question : \r
\n" ); document.write( "\n" ); document.write( "How many different numbers can be formed by taking one, two, three and four digits from the digits 1, 2, 7 and 8, if repetition are not allowed?\r
\n" ); document.write( "\n" ); document.write( "can I do it this way :\r
\n" ); document.write( "\n" ); document.write( " 4P1 x 4P2 x 4P3 x 4P4
\n" ); document.write( "= 4 x 12 x 24 x 24
\n" ); document.write( "= 27648
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Algebra.Com's Answer #351957 by richard1234(7193)\"\" \"About 
You can put this solution on YOUR website!
Not quite. You have to add them because you're taking the number of one-digit numbers, plus the number of two digit numbers, etc. Hence it would be 4+12+24+24 = 64. \n" ); document.write( "
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