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You can put this solution on YOUR website!
\n" ); document.write( "Check out this page
\n" ); document.write( "https://math.stackexchange.com/questions/950502/how-to-find-the-last-non-zero-digit-of-50
\n" ); document.write( "The solution by Edward Jiang is probably the most straight forward process (that doesn't involve any complicated notation or concepts). That solution is the second provided on that page.\r
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\n" ); document.write( "\n" ); document.write( "Recall that the exclamation marks indicate factorial
\n" ); document.write( "Eg: 5! = 5*4*3*2*1
\n" ); document.write( "We can use the rule that
\n" ); document.write( "(b!)/(a!) = b*(b-1)*...*(b-a+1)\r
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\n" ); document.write( "\n" ); document.write( "So for example, if a = 10 and b = 20, then
\n" ); document.write( "(b!)/(a!) = b*(b-1)*...*(b-a+1)
\n" ); document.write( "(20!)/(10!) = 20*(20-1)*...*(20-10+1)
\n" ); document.write( "(20!)/(10!) = 20*19*...12*11
\n" ); document.write( "(20!)/(10!) = 11*12*...*19*20
\n" ); document.write( "Note how we start with 11 (the value just after 10) counting our way up to 20, multiplying along the way.\r
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\n" ); document.write( "\n" ); document.write( "We could rephrase things as such
\n" ); document.write( "(20!)/(10!) = (20*19*...*12*11*10!)/(10!)
\n" ); document.write( "(20!)/(10!) = 20*19*...12*11
\n" ); document.write( "(20!)/(10!) = 11*12*...*19*20
\n" ); document.write( "In the second step, the \"10!\" terms cancel out.\r
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\n" ); document.write( "\n" ); document.write( "We would also say
\n" ); document.write( "(30!)/(20!) = 21*22*...*29*30
\n" ); document.write( "(40!)/(30!) = 31*32*...*39*40
\n" ); document.write( "(50!)/(40!) = 41*42*...*49*50\r
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\n" ); document.write( "\n" ); document.write( "Hopefully this is enough to get you pointed in the right direction.
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