Amazon Free App of the Day - BisMag Calculator 3D
Retails for $1.99, but today it is free.
Here is the product description…
"BisMag Calculator 3D" is a powerful math tool for Android consists of 5 calculators. "Matrix Calculator", a tool to calculate the decompositions and various operations on matrix, "Equation Solver" an instrument capable of solving equations of degree n, "Graphing Calculator" a real scientific graphing calculator can draw graphs in 2D and 3D, "Currency Converter" a currency converter always updated with the new exchange rates and "Unit Converter" a small units converter. In addition we find a comfortable Periodic Table of Elements.