Desmos Scientific Calculator: https://www.desmos.com/scientific
Performs all calculations of scientific calculators including trig functions, logarithms, mean, standard deviation, and counting functions.
Desmos Graphing Calculator: https://www.desmos.com/calculator
This will graph functions, but the abilities of this are endless.
Desmos Matrix Calculator: https://www.desmos.com/matrix
Performs all the basic matrix operations.
Statistics Calculators: https://www.mathportal.org/calculators/statistics-calculator/
Books on Math Study Skills
Books on Math