# Mathedu

Learn math by practice
Lecture 7: Multiplication Exploration
The multiplication between positive integers is a 'long' addition at first glance.
But in Scilab, it is the operator '*', that may be used to multiply any relative integers with different signs, and even 0!
The 'signs rules' for the multiplication are given, after we have explored it in Scilab.
Quiz 5: Multiply Relative Integers
That little Quiz assesses the knoledge of the signs rules, as well as the multiplication by the particular numbers 0, 1 and -1.
Lecture 8: The Ring of Relative Integers with the Addition and the Multiplication
The relative integers set Z has, together with the addition and the multiplication, a so called structure of "ring". This lecture explains the characteristic properties of a ring, always beginning with examples.
There are 2 additional pdf files. "ZplusMultRing" explains more completely the structure of ring and its consequences, in particular the role of parentheses in a formula.
The second pdf file is a serie of solved exercises using the properties of the multiplication together with the addition.