document.write( "Question 294742: the greatest triangular number less than 5000. \n" ); document.write( "
Algebra.Com's Answer #212554 by CharlesG2(834)\"\" \"About 
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the greatest triangular number less than 5000.\r
\n" ); document.write( "\n" ); document.write( "T(sub n) = (n(n+1))/2
\n" ); document.write( "this is also sum of all natural (counting numbers) from 1 to n\r
\n" ); document.write( "\n" ); document.write( "n(n+1) < 10000
\n" ); document.write( "10000 = 100^2
\n" ); document.write( "100 * 101 = 10100
\n" ); document.write( "99 * 100 = 9900
\n" ); document.write( "9900/2 = 4950\r
\n" ); document.write( "\n" ); document.write( "T(sub 99) = 4950 largest triangular number less than 5000\r
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