document.write( "Question 1161225: A child wishes to build up a triangular piles of toy bricks so as to have one brick In the top flow, 2 in the second, 3 in the third and so on . if he has 100 bricks, how many rows can complete and how many bricks has he left \n" ); document.write( "
Algebra.Com's Answer #784725 by ikleyn(52788)\"\" \"About 
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document.write( "A triangular pile with n rows of bricks requires  1 + 2 + 3 + . . . + n = \"%28n%2A%28n%2B1%29%29%2F2\" bricks  (= the sum of the first n natural numbers).\r\n" );
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document.write( "The table is\r\n" );
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document.write( "n  (rows)    1   2   3    4     5     6     7     8     9    10    11   12   13\r\n" );
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document.write( "N (bricks)   1   3   6   10    15    21    28     36   45    55    66   78   91\r\n" );
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document.write( "So, having 100 bricks, the child can build 13-stores pyramid.\r\n" );
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document.write( "He (or she) will use 91 bricks, and 100-91 = 9  bricks will left.\r\n" );
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\n" ); document.write( "\n" ); document.write( "If you want to know the basics for it, it is about arithmetic progressions.\r
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\n" ); document.write( "\n" ); document.write( "For introductory lessons on arithmetic progressions see \r
\n" ); document.write( "\n" ); document.write( "    - Arithmetic progressions\r
\n" ); document.write( "\n" ); document.write( "    - The proofs of the formulas for arithmetic progressions \r
\n" ); document.write( "\n" ); document.write( "    - Problems on arithmetic progressions \r
\n" ); document.write( "\n" ); document.write( "    - Word problems on arithmetic progressions (*)\r
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\n" ); document.write( "\n" ); document.write( "By the way, you will find a picture for your problem in the lesson marked (*) in the list.\r
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\n" ); document.write( "\n" ); document.write( "Also,  you have this free of charge online textbook in ALGEBRA-II in this site\r
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this online textbook under the topic \"Arithmetic progressions\".\r
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\n" ); document.write( "\n" ); document.write( "Save the link to this textbook together with its description\r
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\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-II
\n" ); document.write( "https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson\r
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\n" ); document.write( "\n" ); document.write( "into your archive and use when it is needed.\r
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