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Welcome to NRICH.

ARCHIVE OF OLD THREADS

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Welcome to the AskNRICH archive. Most of the pages in this archive were originally conversations on the AskNRICH web-board, although there has been some editing. We have also included links to the many articles on the site.

You may have come here for specific information about some mathematical topic, or maths-related topic. If you don't find what you are looking for, please do post a question on the web-board.

Each item is labelled with a red number, indicating the rough level of maths involved. Many of the discussions get more difficult as they go on, but the number given gives you an idea of how it starts out. The table below describes the levels, with some examples.

	Description	Examples of topics
2	Primary level maths, usually encountered by age 11	Number problems, shapes
3	Maths usually encountered in the early years of secondary school	Harder number, area, solving simple equations
4	Maths usually encountered around age 14-16	Simultaneous equations, quadratic equations, Pythagoras' theorem
5	Maths usually encountered after age 16	Calculus, complex numbers, trigonometric identities
6	Maths beyond what is normally taught in schools	Lebesgue integration, quantum mechanics, Markov chains

Indexes by area of mathematics Number Whole numbers Number bases Rounding Fractions and percentages Standard form and large numbers Calculators Measures Factors, divisibility and modular arithmetic Square numbers, triangular numbers, etc Prime numbers Infinity and limits Irrational numbers Advanced number theory Miscellaneous Algebra Solving equations Algebraic manipulation Graphs Pythagorean triples Sequences and series Sequences, series and limits Recurrence relations and iteration Inequalities Groups and algebraic structure Matrices Miscellaneous Shape and geometry Shapes and terminology Symmetry Volume, area, perimeter, missing lengths Pi(p) Pythagoras and trigonometry Angles Euclidean geometry proofs Construction and locus Vectors Topology Non-Euclidean geometry 2D, 3D and beyond Maths and art Miscellaneous Statistics and data handling Probability and combinatorics Probability Probability models Combinatorics Graph theory Miscellaneous Trigonometrical, exponential and logarithmic functions Trigonometric functions Trigonometric identities and equations Exponentials and logarithms Series expansions Applications Miscellaneous Calculus Methods of differentiation and integration Particular difficult differentiations and integrations Differential equations Special functions Measure theory Fractional calculus Miscellaneous Complex numbers Basics Euler's formula and de Moivre's theorem Locus Complex numbers and geometry Miscellaneous Physics Speed/distance/time problems Mechanics Quantum mechanics Relativity Black holes, etc Miscellaneous

Other mathematical topics Mathematical games Mathematical puzzles Investigations and proof Paradoxes Computers and mathematics History and philosophy of maths Maths and art/nature Other related topics Teaching and learning maths Use of maths Applying to university STEP preparation Mathematicians, mathematician quotes and jokes Mathematics competitions For younger readers All the discussions marked 2 , collected together. Frequently discussed topics These are the old chestnuts which get asked time and again. Asked NRICH tour A quick tour of the sort of questions that get asked on Ask NRICH, for those who want an idea of what goes on.

If you have any comments, or if you think anything is wrongly classified, please do e-mail the editor.