邏輯和數學

Logic:
http://en.wikipedia.org/wiki/Truth_table
http://en.wikipedia.org/wiki/De_Morgan%27s_laws
http://philosophy.hku.hk/think/logic/puzzles.php
http://www.databasteknik.se/webbkursen/relalg-lecture/index.html
http://en.wikipedia.org/wiki/Bitwise_operation
http://en.wikipedia.org/wiki/Two's_complement
http://en.wikipedia.org/wiki/Arithmetic_shift
http://en.wikipedia.org/wiki/Logical_shift

Maths:
http://en.wikipedia.org/wiki/Trigonometric_functions
http://en.wikipedia.org/wiki/Logarithm
http://en.wikipedia.org/wiki/Inequality_(mathematics)
http://www.ecalc.com/math-help/
http://tutorial.math.lamar.edu/cheat_table.aspx
http://www.intmath.com/methods-integration/7-integration-by-parts.php
http://www.youtube.com/user/patrickJMT
http://patrickjmt.com/
http://www.wolframalpha.com/
http://www.wolframalpha.com/examples/Limits.html
http://www.wolframalpha.com/examples/Derivatives.html
http://www.wolframalpha.com/examples/Integrals.html
http://www.wolframalpha.com/examples/Algebra.html
http://www.wolframalpha.com/examples/Matrices.html
https://www.desmos.com/calculator
http://easycalculation.com/matrix/matrix-inverse.php
http://www.jimmysie.com/maths/matrixinv.php#a=mf&s=3
http://mathrevival.com 

lim(sinx-x)/x^3 as x->0
lim(x/x^3) as x->infinite
d/dx(e^(-x)+xlnx)
integral((sqrt(x+sqrt(x)))
Solve[{2x-y = 0, -x+2y-z = -1, -3+4z = 4},{x,y,z}]
LinearSolve[{{0,1,2,1},{3,0,3,-4},{1,1,1,2},{2,3,1,3}}, {0,7,6,6}]