document.write( "Question 75890: How many four-digit numbers can be formed from the digits 0,1,2,3,4,5 if no repetitions are allowed and 0 cannot be the first digit? \n" ); document.write( "

Algebra.Com's Answer #54564 by kev82(151) $\"\"$ $\"About$

You can put this solution on YOUR website!
Your question is a bit ambiguous, can I use each of those digits once, or as many times as I like?\r
\n" ); document.write( "\n" ); document.write( "If I can only use each digit once, then there are 5 choices for the first digit(1,2,3,4,5), 5, for the second(0,the four that are left), 4 for the third(we've used two), and 3 for the fourth, making 5*5*4*3=300.\r
\n" ); document.write( "\n" ); document.write( "If I can use each digit as many times as I like then there are 5 choices for the first digit and 6 choices for the second, third, and fourth digit, making 5*6*6*6=1080. Interestingly, you can work this out another way. If you think about it, an integer, x, is the number of non-negaitive integers strictly less than it, eg below five there are five non-negative integers 0,1,2,3,4. We are only interested in 4 digit numbers, and are working in base 6 so the answer is clearly

Or going back to decimal,

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\n" ); document.write( "\n" ); document.write( "Hope that helps,
\n" ); document.write( "Kev \n" ); document.write( "

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