Question

Use a number line to find the sum. $$-8+12$$

Short answer

The sum of -8 and 12 is 4.

Step-by-step solution

Position -8 on the number line

The number -8 is 8 units to the left of zero on a number line. Put a mark there.

Move 12 units to the right

After marking -8 on the number line, move 12 units to the right because we are adding 12. Starting at -8, when we move 12 units to the right, we land on 4.

Identify the sum

The final location on the number line after moving 12 units to the right from -8 represents the sum of -8 and 12, which is 4.

Key concepts

Number Line Addition

When it comes to understanding basic arithmetic, the number line is an incredibly powerful tool. It visually represents numbers in a linear format, allowing students to grasp addition and subtraction concepts easily. To add numbers using a number line, simply start at the first number and move to the right for a positive number or to the left for a negative number.

For example, if you're adding 5 and 3, you'd start at 5 on the number line and move 3 units to the right, landing you on 8. It's a physical action that represents the abstract concept of addition, which for many can be a lightbulb moment in their understanding of how numbers work together.

Adding Negative Numbers

Dealing with negative numbers can sometimes be a bit tricky, so it's important to comprehend how they function on the number line. Adding a negative number is the same as subtraction. In other words, if you're at a point on the number line and you add a negative number, it means you have to move to the left.

For instance, if the task at hand is to add -3 to 4. You'd find 4 on your number line and since you're adding a negative number, you'd move three spaces to the left, landing on 1. This visualization helps clarify that adding a negative number reduces the value of the original number.

Integer Operations

Integers include all whole numbers and their negative counterparts, which means that integer operations cover a broad range of mathematical scenarios. When performing operations with integers, it is crucial to understand the rules for addition, subtraction, multiplication, and division, particularly when dealing with positive and negative signs.

In the context of a number line, integer operations can help clarify these rules. For addition, move right for a positive and left for a negative. When subtracting, reverse the direction: move left for a positive and right for a negative. The number line makes these abstract rules concrete and can help students avoid common mistakes when working with integers.