1. The problem asks: What does it mean to use number lines? 2. A number line is a visual representation of numbers on a straight line where each point corresponds to a number. 3. Using number lines helps us understand the position and order of numbers, including positive numbers, negative numbers, and zero. 4. Important rules: - Numbers increase as you move to the right. - Numbers decrease as you move to the left. - Zero is the central point separating positive and negative numbers. 5. Number lines are useful for comparing numbers, performing addition and subtraction, and understanding concepts like absolute value. 6. For example, to add 3 + 2 on a number line, start at 3 and move 2 units to the right, landing on 5. 7. To subtract 4 - 6, start at 4 and move 6 units to the left, landing on -2. Using number lines makes abstract number concepts more concrete and easier to visualize.