2Think about the game!When working with negative numbers, think about what it means in the MathGym-1D game.Which direction does the answer move something? (Is answer is positive or negative?)How far does it move it? (What is the size of the answer? )
3What is an Integer?The integers are made up of the counting numbers, now called the positive integers:1, 2, 3, 4, …The negative numbers-1, -2, -3, -4, …And zero
4More Words to LearnWe will use the capital letter Z (from the German word “zahlen”) to denote the set of integers.The positive numbers should be written as +1, +2, +3, +4, …, but we usually drop the + as unnecessary.The symbols + and – are called the sign of the number.
5The Basics The game shows that -(-3) = 3, so 3 + (-3) = 0 and (-3) + (-(-3)) = 0You can see thatn + (-n) = 0for every integer n.Alson + 0 = 0 + n = nfor every n.
6Absolute valueThe absolute value or magnitude or size of a number is how far it moves something, regardless of direction.Compute it by dropping the sign.It is always greater than or equal to 0.
7The Number LineLay out equally spaced points on a line and label them with the integers:The numbers act just like street addresses, they tell you where to go.The arrow points in the positive direction.Later we will make up new numbers to give addresses to the other points.