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1.1 K) Negative Numbers – Adding & Subtracting
1.1 K) Negative Numbers – Adding & Subtracting
The best way to work out addition or subtraction calculations with negative numbers is to use a number line. The number line does not have to be incredible detailed; instead it should give you a rough idea of where the numbers are located on the number line. An example of a number line is given below.
Whenever we are adding a number to any number (positive or negative), we are moving towards the right on our number line.
Whenever we are taking a number from any number (positive or negative), we are moving towards the left on our number line.
Whenever we are taking a number from any number (positive or negative), we are moving towards the left on our number line.
Example 1
Complete the calculation:
Complete the calculation:
The first step in answering this question is to find -7 on the number line.
We are adding 4 to -7, which means that we are going to move 4 towards the right, which results in the answer being -3.
Example 2
Complete the calculation:
Complete the calculation:
Like before, the first step is to locate -6 on the number line.
We are adding 9 to -6, which means that we are going to move 9 to the right. This is going to move us into the positive values. Therefore, we split the adding of 9 into two different numbers; one number to get us to 0, and the next number is the remaining amount that needs to be added. Our number is -6 and in order to get to get to 0, we need to add 6. We want to add 9 in total, which means that there is another 3 to add on from zero. This results in the answer being 3.
Example 3
Complete the calculation:
Complete the calculation:
Like before, the first step is to locate 15 on a number line (we only need to roughly locate it).
We are taking 22 from 15, which means that we are moving 22 towards the left and this will result in a negative outcome. In order to get to 0 from 15, we take 15. When we are at 0, we need to take another 7 because we are taking 22 and not 15. This results in the answer being -7.
Example 4
Complete the calculation:
Complete the calculation:
The start value for this question is -6 and a sketch of where this is located on a number line is given below.
We are taking 11 away from -6, which means that we are going to move 11 towards the left, which results in the answer being -17.
Final Note
Working with negative numbers is fairly straight forwards when we draw a quick sketch of a number line; the sketch does not have to have an excessive amount of detail, instead it just gives you an idea of where the numbers are located and it ensures that you go in the correct direction (towards the right when adding and towards the left when subtracting).
Also, for adding or subtracting numbers that take you across zero (from negative to positive, or from positive to negative), it is a good idea to split the number that is being added or subtracted into two numbers; what gets you to zero and then the remainder that needs to be added or subtracted. We did this during examples 2 and 3.
Working with negative numbers is fairly straight forwards when we draw a quick sketch of a number line; the sketch does not have to have an excessive amount of detail, instead it just gives you an idea of where the numbers are located and it ensures that you go in the correct direction (towards the right when adding and towards the left when subtracting).
Also, for adding or subtracting numbers that take you across zero (from negative to positive, or from positive to negative), it is a good idea to split the number that is being added or subtracted into two numbers; what gets you to zero and then the remainder that needs to be added or subtracted. We did this during examples 2 and 3.