Pieter Geerkens
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 Mar14 revised Does the square or the circle have the greater perimeter? A surprisingly hard problem for high schoolers added 3 characters in body Mar14 revised Does the square or the circle have the greater perimeter? A surprisingly hard problem for high schoolers added 66 characters in body Mar14 revised Does the square or the circle have the greater perimeter? A surprisingly hard problem for high schoolers added 30 characters in body Mar14 answered Does the square or the circle have the greater perimeter? A surprisingly hard problem for high schoolers Mar2 awarded Yearling Jan19 comment Can you be 1/12th Cherokee? @EricLippert: It depends on whether you are counting backwards to a point in time, or to a number of generations. For many people it makes more sense to count backwards to a point in time, for which this means of counting makes sense. As others have pointed out, all methods of counting ancestry are approximations at best since 99% of all our genes are identical across the entire human race. Jan19 answered Can you be 1/12th Cherokee? Mar22 comment Why do we require radians in calculus? @Ruslan: No, how can you say that on a Mathematics site! There is a world of difference between N⋅m and J; namely that one measures the magnitude of a pseudo-vector, and the other the magnitude of a vector. Mar2 awarded Yearling Jan23 answered What is the difference between a point and a vector Jan13 awarded Autobiographer Dec22 comment 'mod' or 'remainder' symbol valid in maths? Thank you for the motivation to read Eric's post closely once again; you are correct. Dec22 comment 'mod' or 'remainder' symbol valid in maths? @BillDubuque: The % operator in C-like languages does not respect the equivalence classes of a finite ring over the integers under normal multiplication and addition when one or more operands is negative. Forgive me if my terminology is not spot on - it has been almost 4 decades since I last did the algebra rigorously. Dec22 comment 'mod' or 'remainder' symbol valid in maths? +1 for noting that % is a remainder operator in C-like languages, and not a modulo operator. Dec22 comment 'mod' or 'remainder' symbol valid in maths? The percent operator in 'C'-like languages is a remainder operator not a modulo operator. Why Kernighan and Ritchie made this decision is lost in the mists of time, but it is unfortunate. Here is an article on the difference by one of the world's C# experts: blogs.msdn.com/b/ericlippert/archive/2011/12/05/… Dec13 comment Of any 52 integers, two can be found whose difference of squares is divisible by 100 Nice generalization of the technique used above by @Matthew Conroy. Nov22 comment game combinations of tic-tac-toe Accounting for symmetry, this can quickly be reduced by a factor of 6, as there are only 12 possible two move openings, not 8*9=72. Nov10 comment How to put 9 pigs into 4 pens so that there are an odd number of pigs in each pen? I have known this question/riddle for nearly half a century, and never expected to see still another good valid answer. Nov9 comment Is my proof correct for: $\sqrt[7]{7!} < \sqrt[8]{8!}$ Beat me to it. Well done. Oct18 answered Finding the equation for a tangent line at a certain point