What is the number line?
The number line is a line simply just a line that has numbers labelled at equal distances along the line. You can write the numbers down the line as far as you want and there are no rules on how far apart the numbers should be! There is also no rule of where to start your number line as long as it fits the numbers that are important for the question you are working on. Here’s an example of a number line that shows negative and positive numbers around a middle value of 0:
How to use this concept?
To use a number line, you first need to know that each number is placed in its spot based on how large or small they are. So, if you need to find the number 10, you can go right along the number line until you reach ten. Another way you can use the number line is to compare two numbers. For example, if you wanted to know how far apart are 7 and 10 from each other, you can count how many jumps it takes going from 7 to 10. In other others, this would be finding the subtraction of 7 from 10 (10 – 7 = 3). You can not only use it for subtraction but also addition.
Sample Math Problems
Question:
Which of the following numbers are less than 3? Hint: There could be more than one answers!
A) -2
B) 3
C) 2
D) 33
Solution:
Option A and C are correct. Both -2 and 2 and lesser than 3.
Note: A common confusion is that option B is also correct but it is not. The question asks which number is less than 3, not less than or equal to 3. Therefore, we are looking for numbers to the left of the three on the number line.
Question:
Which of the following numbers on the number line is 2 greater than 5?
A) 4
B) 7
C) 3
D) 8
E) 12
Solution:
Option B is correct.
The question is asking which number is 2 + 5 = 7. To do this you have to start at 5 and jump 2 places to the right on the number line to get to 7.
Question:
What number is 3 less than -6? Hint: Use the number line for help.
Solution:
-9 is the correct answer.
To find a number lesser than another number you need to move left on the number line. So, for this question, you need to start at -6, then move 3 spaces to the left, which would get you at -9. So, -9 is the answer.
Question:
The average temperatures in December in the following cities are below:
Athens (A) 10°C
Barcelona (B) 9°C
Chicago (C) 7°C
Draw a number line with the appropriate numbers and spacing to fit the above temperatures on the number line. Label the points by A, B, C for each city accordingly.
Solution:
The correct number line is drawn as below:
