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1.1 M) Multiplying & Dividing Negative Numbers
1.1 M) Multiplying & Dividing Negative Numbers
There are a few different rules that we need to follow when we are multiplying and dividing negative or positive numbers.
If we are multiplying or dividing two numbers with different signs, the outcome will be negative. This is the case for:
If we are multiplying or dividing two numbers with different signs, the outcome will be negative. This is the case for:
If we are multiplying or dividing two numbers that have the same sign, the outcome with be positive. This is the case for:
The best way to answer the examples that we are going to look at is to find what the sign is and then find out what the number is.
Example 1
Complete the calculation:
Complete the calculation:
We are multiplying a positive by a negative and we know that opposite signs will give us a negative. Therefore, our answer will be negative. We now move on to the numbers. We are multiplying 7 by 4, which is 28. This combined with the negative sign results in the answer being -28.
Example 2
Complete the calculation:
Complete the calculation:
We are dividing a negative by a positive, which means that the answer will be negative. We now divide 64 by 4 and I am going to do this by using the bus stop method (click here for a more detailed look at how the bus stop method works).
From the bus stop method, we can see that 64 divided by 4 is 16. We now combine the 16 with the sign. We found out earlier that the sign in negative. Therefore, the answer to this question is -16.
Example 3
Complete the calculation:
Complete the calculation:
Both of these numbers are negative, which means that the answer is going to be positive (signs that are the same result in a positive answer). We now multiply out the numbers; 8 x 7, which is 56. Therefore, the answer to this question is 56.
End Note
Multiplying and dividing positive and negative numbers becomes so much easier if we split the calculation up into the sign and then the numbers. The key rules to remember are that:
It is worth getting the rules at the start of this section down on a revision card.
Multiplying and dividing positive and negative numbers becomes so much easier if we split the calculation up into the sign and then the numbers. The key rules to remember are that:
- Multiplying and dividing numbers that have the same sign results in a positive number
- Multiplying and dividing numbers that have different signs results in a negative number
It is worth getting the rules at the start of this section down on a revision card.