document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=445787>Question 445787</A>: <I><SPAN STYLE=\"word-break: break-all;\"> To keep computer files secure, many programs require the user to enter a password. The shortest allowable passwords are typically six characters long and can contain both numbers and letters. How many six-character passwords are possible if (a) characters can be repeated and (b) characters cannot be repeated?\r<BR>\n" );
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document.write( "on (a) this is what i tried... 26^6 x 26^5 x 10 x 26^4 x 10^2 etc. but the number I get is way off from the back of the book I also tried 36P6 but that was also incorrect. I have no idea how to continue input would be much appreciated :)<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #307753 by </B><A HREF=/tutors/aboutme.mpl?userid=sudhanshu_kmr><B>sudhanshu_kmr(1152)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=sudhanshu_kmr><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=sudhanshu_kmr><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=307753\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <BR>\n" );
document.write( "any position can be fill by 36 ( 26+10) characters.\r<BR>\n" );
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document.write( "(a) no. of possible password = 36*36*36*36*36*36 =  2176782336\r<BR>\n" );
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document.write( "(b) no. of possible password when repetition not allowed = 36P6 = 1402410240\r<BR>\n" );
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