document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=255054>Question 255054</A>: <I><SPAN STYLE=\"word-break: break-all;\"> How many different four-digit numbers can be formed using the digits 1, 1, 9, and 9? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #187323 by </B><A HREF=/tutors/aboutme.mpl?userid=CharlesG2><B>CharlesG2(834)</B></A><img src=\"/images/stars/stars-11.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=CharlesG2><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=187323\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> How many different four-digit numbers can be formed using the digits 1, 1, 9, and 9?<BR>\n" );
document.write( "1199<BR>\n" );
document.write( "1919<BR>\n" );
document.write( "1991<BR>\n" );
document.write( "9119<BR>\n" );
document.write( "9191<BR>\n" );
document.write( "9911<BR>\n" );
document.write( "combination formula, or the number of ways to combine k items from a set of n:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=C%28n%2Ck%29+=n%21%2F%28%28n-k%29%21k%21%29 ALIGN=MIDDLE  ALT=\"C%28n%2Ck%29+=n%21%2F%28%28n-k%29%21k%21%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "there are 4 numbers so n=4<BR>\n" );
document.write( "there are only 2 different numbers we are actually choosing so k=2<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=C%28n%2Ck%29+=4%21%2F%28%284-2%29%212%21%29 ALIGN=MIDDLE  ALT=\"C%28n%2Ck%29+=4%21%2F%28%284-2%29%212%21%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=C%28n%2Ck%29+=%284%2A3%2A2%2A1%29%2F%282%212%21%29 ALIGN=MIDDLE  ALT=\"C%28n%2Ck%29+=%284%2A3%2A2%2A1%29%2F%282%212%21%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=C%28n%2Ck%29+=24%2F%282%2A1%2A2%2A1%29 ALIGN=MIDDLE  ALT=\"C%28n%2Ck%29+=24%2F%282%2A1%2A2%2A1%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=C%28n%2Ck%29+=24%2F4 ALIGN=MIDDLE  ALT=\"C%28n%2Ck%29+=24%2F4\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=C%28n%2Ck%29+=6 ALIGN=MIDDLE  ALT=\"C%28n%2Ck%29+=6\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );