In ancient China , values for π included (around 1 AD), √ 10 (100 AD, approximately ), and 142 / 45 (3rd century, approximately ).  Around 265 AD, the Wei Kingdom mathematician Liu Hui created a polygon-based iterative algorithm and used it with a 3,072-sided polygon to obtain a value of π of .   Liu later invented a faster method of calculating π and obtained a value of with a 96-sided polygon, by taking advantage of the fact that the differences in area of successive polygons form a geometric series with a factor of 4.  The Chinese mathematician Zu Chongzhi , around 480 AD, calculated that π ≈ 355 / 113 (a fraction that goes by the name Milü in Chinese), using Liu Hui's algorithm applied to a 12,288-sided polygon. With a correct value for its seven first decimal digits, this value of ... remained the most accurate approximation of π available for the next 800 years. 
Hello, I was just wondering is there any difference in scoring of academic and general writing ? I felt, the vocab section in academic test , requires more academic not, candidates will not score a 7 or 8 in it (?????). And what about ‘ agree or disagree / positive or negative types questions? Is it necessary to stick with one side in the opinion paragraph? ie; 2 positive points and 1 negative point. Can I still conclude it as ‘positive’ ? Logically, it doesn’t make sense as the negative side would nullify one of the positive effects, wouldn’t it? Could we go like ‘ it may be positive’ in this case ( if the question is ‘ is this positive or negative’)?