document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=321179>Question 321179</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Which of these digits is the units digit of the number 9^99 &#8722;4^44?\r<BR>\n" );
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document.write( "A) 4 B) 3 C) 9 D) 5 E) 1 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #230021 by </B><A HREF=/tutors/aboutme.mpl?userid=toidayma><B>toidayma(44)</B></A><img src=\"/images/stars/stars-07.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=toidayma><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=toidayma><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=230021\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> In order to know the unit digit of this calculation, you have to know the digit of each number. <BR>\n" );
document.write( "For 9^99, notice that 9^1 = 9, 9^2 = 81, 9^3 = ...9, and so on.<BR>\n" );
document.write( "So the unit digit of 9^n with n is an odd number (99) is 9.(and if n is even, the unit digit is 1)<BR>\n" );
document.write( "For 4^44, notice that 4^1 = 4, 4^2 = ..6, 4^3 = ...4, and so on.<BR>\n" );
document.write( "So the unit digit of 4^n with n is an even number (44) is 6 (and if n is odd, the unit digit is 4).<BR>\n" );
document.write( "Therefore, the unit digit of 9^99 - 4^44 = 9 - 6 = 3. Choose  answer choice B. </SPAN>\n" );
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