Multiplying and dividing negative numbers in math can be fairly straightforward if you follow these two rules:
a) If the two numbers have different signs you get a negative answer.
b) If the two numbers have the same signs you get a positive answer.
Let’s take a look at some examples:
Work out -7 × 4.
First multiply 7 by 4 to give you 28. Then, decide if your answer is positive or negative by following the two rules above. Since 7 is a negative number (-7) and 4 is positive (+4), the signs are different so you get a negative answer. Therefore the answer is -28.
Work out -6 × -5.
Again work out 6 × 5 which is 30. This time both of the numbers you are multiplying are negative numbers, so they both have the same sign. Therefore you get a positive answer, so the answer is +30.
Work out 48 ÷ -6.
Again, first work out 48 ÷ 6 which gives 8. The two numbers that we are dividing this time have different signs, so your answer is going to be negative (Answer = -8).
Work out -56 ÷ -8.
Firstly work out 56 ÷ 8 which gives 7. So the answer is either positive 7 or negative 7, depending on the signs of the numbers in the question. In the question, 56 is negative, and 8 is also negative – so both numbers have the same types of signs. Therefore, you get a positive answer of 7.
You can also follow these four rules:
A positive times (divide) a positive gives a positive (+ × + = +).
A negative times (divide) a positive gives a negative (- × + = -).
A positive (divide/times) a negative gives a negative (+ × – = -).
A negative (times/divide) a negative gives a positive (-×- = +).
Also remember that these rules only work on two numbers at a time!