document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=621710>Question 621710</A>: <I><SPAN STYLE=\"word-break: break-all;\"> please help and explain?   7*?&#8801; 8(mod9) </SPAN>\n" );
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document.write( "a=b(mod n)\r<BR>\n" );
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document.write( "if their difference a &#8722; b is an integer multiple of n. The number n is called the modulus of the congruence.\r<BR>\n" );
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document.write( "so:\r<BR>\n" );
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document.write( "7x=8(mod9); 7x - 8 has to be a multiple of 9, trying iterative values:\r<BR>\n" );
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document.write( "7(1) - 8 = -1 no\r<BR>\n" );
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document.write( "7(2) - 8 = 6 no\r<BR>\n" );
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document.write( "7(3) - 8 = 13 no\r<BR>\n" );
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document.write( "7(4) - 8 = 20 no\r<BR>\n" );
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document.write( "7(5) - 8 = 27 yes\r<BR>\n" );
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document.write( "7*5 = 8(mod9)<BR>\n" );
document.write( " </SPAN>\n" );
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