Period+6


 * 1) Properties of Matrices:
 * 2) Size (order)
 * 3) Square matrix
 * 4) Column and row matrix
 * 5) Identity matrix
 * 6) Matrix Arithmetic and Operations
 * 7) Addition/Subtraction
 * 8) Scalar Multiplication
 * 9) Transpose
 * 10) Multiplication
 * 11) Applying Matrices to Linear Systems
 * 12) Inverse of a 2x2 matrix
 * 13) Solving a system of 2 equations in 2 unknowns (using the Inverse)
 * 14) Determinants
 * 15) Determinant of a 2 x 2
 * 16) Determinant of a 3 x 3
 * 17) Cramer’s Rule
 * 18) Cramer's Rule for a 2x2 system
 * 19) Cramer’s Rule for a 3 x 3 system