Multiplying and dividing positive and negative numbers

Multiplying and dividing positive and negative

numbers

Slideshow 5, Mr Richard SasakiRoom 307

Objectives• Multiplication and division drill• Learn rules for multiplying negative

numbers• Learn rules for dividing negative

numbers• Practice multiplying and dividing

negative numbers

You have four minutes to complete the drill, good luck!

Answers1212272416312454036

4352443503240200

31430154610713216

Multiplying with Negative NumbersRules for multiplying negative numbers are similar to adding or subtracting.

Double .Example

Let’s look at the number line.

If we double , we double its “size”. As it’s negative it must go further to the left.

×2

We double and come to . This is the same as and taking away another .

Numerically,Double .

Multiplying with Negative NumbersLet’s try another example.ExampleCalculate .So here we extend four times and reach .

(−5 )×4¿−20Basically, if we multiply a negative number by a positive, we get a negative.

Multiplying with Negative NumbersHow about two negatives?ExampleCalculate Here we increase the weight of -5, but it goes the opposite way as it’s by a negative amount.

¿30When we multiply a negative number by another, the answer will be positive.

Dividing Negative NumbersDividing has exactly the same rules.ExamplesCalculate .10÷(−5)¿−2It doesn’t make any difference which number in the calculation is negative. If one is negative, the answer will be negative.

Calculate .(−18)÷6¿−3

Dividing Negative NumbersLike multiplication, if we divide a negative number by another, our result is positive.ExamplesCalculate .

Calculate . (−60)÷ (−6)¿10(−5 )×8÷(−2)¿

¿20

Answers - Easy−15−36−10−3621

−90,000𝑌𝑒𝑛

−3−3−525−4−1072−5

Answers - Medium

−1−2−3−4−2−4−6−8−3−6−9−12−4−8−12−16

−6031−121−4

1𝑑𝑒𝑔𝑟𝑒𝑒𝑠10.25

Answers - Hard8−2410812−0.5

−53𝑚−38𝑚

2

16

−64