2||0|80|0|
0|0|0|||||Surprising results from a competition of the 7-graders|nikolinv||19:12:31|05/09/2011|Surprising results from a competition of the 7-graders.%0D%0A%0D%0ALevel%3A Districts of Serbia.%0D%0AAge%3A 13.%0D%0A%0D%0A1. a%5E2 %2B b%5E2 - 2a %2B6b %2B 10 %3D 0. Calculate a%5E2009 - 2009b.%0D%0A%0D%0A2. If AD %3D 9 cm%2C BD %3D 16 cm%2C find area and perimeter of the right angled triangle ABC %28AB is hypotenuse%2C D is foot of the altitude from C%29.%0D%0ARemark%3A Euclid%27s theorem and similarity is not allowed%2C only P.T.%0D%0A%0D%0A3. Is it number 2009%2A2011-48 composite. Explain.%0D%0A%0D%0A4. Geometry.%0D%0A%0D%0A5. Find for digits number %5Babcd%5D. Conditions are%3A%0D%0Aa%2Bb%2Bc%2Bd %3D a%2Ab %3D %5Bcd%5D. %28 One solution is number 2714%2C 2%2B7%2B1%2B4%3D2%2A7%3D14%29.  %0D%0A%0D%0AResults%3A%0D%0A%0D%0A1. 50%25%0D%0A2. 75%25%0D%0A3. 19%25 %3F%3F%3F%0D%0A%0D%0A5. 60%25%0D%0A%0D%0A3. Formula %28a-b%29%28a%2Bb%29 %3D a%5E2-b%5E2  is very well known for all student at this age%2C but it wasn%27t help. Problem is in application of this formula.   %0D%0A%0D%0A%0D%0ASource%3A http%3A%2F%2Fmatematicar.com%2Frezultati%2FOKRUZNO%25202011-GANE1.xls%0D%0A
2|1|0|||||RE%3A Surprising results from a competition of the 7-graders|alexb||23:08:07|05/09/2011|Yes%2C this is a curious statistics.%0D%0A%0D%0A2009%2A2011 - 48 %3D 2010%5E2 - 49 %3D 2003%2A2017%0D%0A%0D%0AI had a look at the xls file. Serbian is very much like Russian.%0D%0A%0D%0AThankyou for the problems and statistics%0D%0A%0D%0A