An interactive boosts mathematicians' knowledge of subtracting integers using a horizontal number line by way of multiple-choice, true or false, and discussion questions. 

Students solve matrices by multiplication. In this algebra lesson, students create coded messages and relate it to solving matrices. They multiply and find the inverse of matrices.

Students perform operations with matrices. In this algebra lesson, students use cryptography and cryptanalysis to solve problems. They add, subtract, and multiply matrices.

Pupils perform basic operations in modular (clock) arithmetic. Students encode and decode messages using shift and affine ciphers. Pupils apply their multiplication, division, addition, and subtraction skills.