document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=115912>Question 115912</A>: <I><SPAN STYLE=\"word-break: break-all;\"> How many 7-digit telephone numbers are possible if the first digit cannot be 0 and\r<BR>\n" );
document.write( "\n" );
document.write( "(a) only odd digits may be used?<BR>\n" );
document.write( "(b) the telephone number must be a multiple of 10 (that is, it must end in 0)<BR>\n" );
document.write( "(c) the telephone number must be a multiple of 100?<BR>\n" );
document.write( "(d) the first 3 digits are 481<BR>\n" );
document.write( "(e) no repetitions are allowed? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #84354 by </B><A HREF=/tutors/aboutme.mpl?userid=checkley71><B>checkley71(8403)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=checkley71><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=84354\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a) options are 1,3,5,7,9 thus the choices are: 5^7=78,125 possible combinations.<BR>\n" );
document.write( "b) options are 0,1,2,3,4,5,6,7,8,9 for the first 6 digits & only 1 option for the last digit: thus 10^5*1=100,000+1-100,001 possible combinations.<BR>\n" );
document.write( "c)options are 0,1,2,3,4,5,6,7,8,9 for the first 5 digits & 1 each for the last 2 digits: thus 10^4*181=10,000+1+1=10,002 possible combinations.<BR>\n" );
document.write( "d) 1 choice for the first 3 digits which leaves 10 choices for the next 4 positions or 1+10^4=1+10,000=10,001.<BR>\n" );
document.write( "e) 10*9*8*7*6*5*4=604,800 choices.  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );