A number line is a line drawing where numbers are written from smallest to largest. Number lines can be a tool for doing simple math problems. This is the most useful way to do problems with small numbers. If your math problem involves numbers greater than 20 or fractions, it may be a little difficult to use this tool. The number line is the easiest to use to help you add and subtract small numbers. You can also use it to work on problems with negative numbers.
Step
Method 1 of 6: Constructing a Number Line
Step 1. Draw a long line on a piece of paper
This line will be the basis of your number line.
You can draw it with a pen or marker if you want to use your number line over and over again
Step 2. Draw a delimiter on your number line
These delimiters will make your long lines look like railroad tracks.
You can also make markers with a pen so you can use the number line for more than one question
Step 3. On the left side, start writing the number above the delimiter
Start at zero above the first delimiter, on the left side.
- At each delimiter, write the next number. For example, above the delimiter next to zero, write 1.
- You can also write these numbers with a pen, so you can use this number line over and over again.
Step 4. Stop writing numbers up to 20
Remember, doing math problems with numbers greater than 20 will make this method too difficult.
Now, your number line goes from 0 to 20, from left to right
Method 2 of 6: Adding on the Number Line
Step 1. Look at your math problem
Find the first and second numbers in the problem.
For example, in 5 + 3, the first number is 5 and the second number is 3
Step 2. Find the first number in your addition problem on your number line
Place your finger on the number.
- It is at this number that you will start counting.
- For example, if your math problem is 5 + 3, you should put your finger on 5 on your number line.
Step 3. Slide your finger to the right, to the next delimiter and number
Now you have moved 1 step.
If you start at 5, when you reach 6, then you have moved 1 step
Step 4. Slide your finger a few steps, as many as the second number in your addition problem, then stop
This will ensure that you stop at the answer to your question.
- Don't move more steps than the second number in your addition problem.
- For example, if the second number in your problem is 3, then you will move 3 steps.
Step 5. Look at the number that is now on your finger
That number is the answer to your math problem.
For example, if your math problem is 5 + 3, you will move 3 steps to the right from 5. Your finger will be on the 8 on your number line. 5 + 3 = 8
Step 6. Repeat this method to check your answers
This will help you make sure that you get the correct answer to the math problem.
If you find a different answer when you double-check, try again to double-check the answer
Method 3 of 6: Subtracting with a Number Line
Step 1. Look at your subtraction problem
Find the first and second numbers in the problem.
In questions 7 - 2, 7 is the first number in the problem and 2 is the second number in the problem
Step 2. Find the first number of your subtraction problem on your number line
Place your finger on the number.
If your math problem is 7 - 2, you'll start putting your finger on the 7 on your number line
Step 3. Slide your finger to the left, to the next delimiter and number
Now, you have moved 1 step.
For example: if you start at 7, when you reach 6, then you have moved 1 step
Step 4. Slide your finger a few steps, as many as the second number in your math problem, then stop
This will ensure that you stop at the answer to your question.
If the second number in your problem is 2, then you have to slide your finger two steps to the left
Step 5. Look at the number that is now on your finger
That number is the answer to your subtraction problem.
For example, in problem 7 - 2, you would start your problem from 7 on your number line. You will move 2 steps to the left, stopping your finger at 5 on your number line. 7 – 2 = 5
Step 6. Repeat this method from the beginning
This is done to check your answers.
If you get a different result from your test, try again to see where you went wrong
Method 4 of 6: Creating a Number Line with Negative Numbers
Step 1. Create a new number line
Start by drawing a long horizontal line on a piece of paper.
This line will be the basis of your number line
Step 2. Draw a delimiter on your number line
These delimiters will make your long lines look like railroad tracks.
You'll need to create more delimiters on the number line (compared to delimiters for simple addition/subtraction problems) if you're working with negative numbers
Step 3. Start writing the numbers on your delimiter
Insert a zero in your delimiter in the middle of your number line.
Enter 1 to the right of zero and -1 to the left of zero. -2 is to the left of -1 and so on
Step 4. Look at your finished number line
Zero should be in the middle.
Try writing numbers up to 20 on the right and -20 on the left
Method 5 of 6: Adding with Negative Numbers
Step 1. Look at your math problem
Find the first and second numbers in the problem.
For example, in 6 + (-2), 6 is the first number, and -2 is the second number
Step 2. Place your finger on your number line
Place your finger on the first number in your problem.
In 6 + (-2), you will start placing your finger on the 6 on your number line
Step 3. Slide your finger to the left, to the next delimiter and number
Adding negative numbers is pretty much the same as subtraction. Now you have moved 1 step.
Step 4. Slide your finger to the left a few steps, as many as the second number in your problem, then stop
This will ensure that you stop at the answer to your question.
For example, if the second number in your problem is -2, you will need to slide your finger two steps to the left
Step 5. Look at the number that is now on your finger
This number is the answer to your addition problem.
For example, if your problem was 6 + (-2), you would start with your finger at 6. You would slide your finger two steps to the left, ending at 4. 6 + (-2) = 4
Step 6. Repeat this method again
This is done to check your answers.
If you get a different answer while checking your question, try again to see where you went wrong
Method 6 of 6: Subtracting by Negative Numbers
Step 1. Use your negative number line
You need numbers less than zero and more than zero.
Remember, on your negative number line, zero will be in the middle. All negative numbers will be to the left of zero and all positive numbers will be to the right of zero
Step 2. Look at your subtraction problem
Find the first and second numbers in the problem.
For example, in (-8) - (-3), the first number is -8 and the second number is -3
Step 3. Place your finger on the first number in the problem
This is where you will start.
If your problem was (-8) - (-3), you would place your finger on the number -8 on your number line
Step 4. Slide your finger to the right, to the next delimiter and number
Subtracting negative numbers is much the same as adding regular numbers.
If you started at -8, you should be at -7 by now. You have moved one step
Step 5. Slide your finger a few steps, as many as the second number in your problem, then stop
This will ensure that you stop at the answer to your question.
For example, if the second number in the problem is -3, you only need to move 3 steps down your number line
Step 6. Look at where your finger is on your number line
That number is the answer to your subtraction problem.
For example, in (-8) - (-3), you would start your finger at -8 and move 3 steps to the right, ending at -5. (-8) - (-3) = -5
Step 7. Repeat this question again
This is done to check your answers
If you don't get the same answer this time, try again to see where you went wrong
Tips
- It is easiest to use the number line for problems involving integers. Avoid decimals and fractions.
- Using this method for large numbers will take up a lot of time and make it easier for you to make mistakes.
- Use this method for small numbers.
