Examples with solutions for Multiplication and Division of Signed Mumbers: Using order of arithmetic operations

Exercise #1

Solve the following problem:

−400:(−7−13+10)= -400:(-7-13+10)=

Video Solution

Step-by-Step Solution

First, let's solve the expression in parentheses from left to right:

−7−13=−20 -7-13=-20

−20+10=−10 -20+10=-10

Now the expression we have is:

−400:−10= -400:-10=

Let's note that we are dividing two negative numbers, so the result must be a positive number:

−−=+ \frac{-}{-}=+

Therefore:

40010=40 \frac{400}{10}=40

Answer

+40 +40

Exercise #2

Solve the following equation:

−(−7+4):(−9)= -(-7+4):(-9)=

Video Solution

Step-by-Step Solution

In order to solve the equation we must follow the order of operations beginning with the parentheses:

−7+4=−3 -7+4=-3

We should obtain the following expression:

−(−3):(−9)= -(-3):(-9)=

Let's apply the rule:

−(−x)=+x -(-x)=+x

Therefore:

−(−3)=3 -(-3)=3

Resulting in the following expression:

3:(−9)= 3:(-9)=

Let's proceed to write the expression as a simple fraction:

+3−9= \frac{+3}{-9}=

Note that we are dividing a positive number by a negative number, so the result must be a negative number:

+−=− \frac{+}{-}=-

Next let's expand the 9 in the denominator of the fraction:

−33×3= -\frac{3}{3\times3}=

Finally let's reduce the 3 in both the numerator and denominator of the fraction:

−13 -\frac{1}{3}

Answer

−13 -\frac{1}{3}

Exercise #3

−3.5:−7+14= ? -3.5:-7+14=\text{ ?}

Video Solution

Step-by-Step Solution

We must solve the exercise from left to right.

First, we will rewrite the division as a simple fraction in the following way:

−3.5−7+14= \frac{-3.5}{-7}+14=

Note that we are dividing a negative number by a negative number, so the result must be a positive number:

−−=+ \frac{-}{-}=+

We will then break down 7 into a multiplication exercise:

3.53.5×2+14= \frac{3.5}{3.5\times2}+14=

Finally, we will reduce the 3.5 in both the numerator and denominator of the fraction to get our answer:

12+14=1412 \frac{1}{2}+14=14\frac{1}{2}

Answer

+1412 +14\frac{1}{2}

Exercise #4

−12:−6⋅(−8+4)= -12:-6\cdot(-8+4)=

Video Solution

Step-by-Step Solution

Let's first solve the expression in parentheses:

−8+4=−4 -8+4=-4

Now the expression is:

−12:−6×−4= -12:-6\times-4=

Let's solve the expression from left to right.

We'll write the division as a simple fraction like this:

−12−6= \frac{-12}{-6}=

Note that we are dividing between two negative numbers, so the result must be a positive number:

−−=+ \frac{-}{-}=+

Therefore:

126=2 \frac{12}{6}=2

Now the expression we got is:

2×−4= 2\times-4=

Note that we are multiplying a positive number by a negative number, so the result must be a negative number:

+×−=− +\times-=-

Therefore the result is:

2×−4=−8 2\times-4=-8

Answer

−8 -8

Exercise #5

Solve the following equation:

38:(−4)⋅12:(−3)= 38:(-4)\cdot12:(-3)=

Video Solution

Step-by-Step Solution

Let's begin by writing the two division exercises as a multiplication of two simple fractions:

(38:(−4))×(12:(−3))= (38:(-4))\times(12:(-3))=

38−4×12−3= \frac{38}{-4}\times\frac{12}{-3}=

Let's proceed to combine them into one exercise:

38×12−4×−3= \frac{38\times12}{-4\times-3}=

Note that in the denominator of the fraction we are multiplying two negative numbers, therefore the result must be positive:

38×124×3= \frac{38\times12}{4\times3}=

Let's now break down the 12 in the fraction's numerator into a multiplication exercise:

38×4×34×3= \frac{38\times4\times3}{4\times3}=

Finally let's reduce the multiplication exercise 4X3 in the numerator and denominator and we should obtain the following:

38 38

Answer

38 38

Exercise #6

Solve the following equation:

−49:−7⋅3⋅−14= -49:-7\cdot3\cdot-\frac{1}{4}=

Video Solution

Step-by-Step Solution

Let's begin by writing the division exercise as a simple fraction:

−49−7×3×(−14)= \frac{-49}{-7}\times3\times(-\frac{1}{4})=

Note that we are dividing between two negative numbers, therefore the result must be positive:

497×3×(−14)= \frac{49}{7}\times3\times(-\frac{1}{4})=

Let's proceed to solve the division exercise:

7×3×−14= 7\times3\times-\frac{1}{4}=

Let's now solve the exercise from left to right:

7×3=21 7\times3=21

We should obtain the following exercise:

21×−14= 21\times-\frac{1}{4}=

Note that we are multiplying a positive number by a negative number, therefore the result must be a negative number:

−214 -\frac{21}{4}

Let's write the result as a mixed fraction:

−214=−514 -\frac{21}{4}=-5\frac{1}{4}

Answer

−514 -5\frac{1}{4}

Exercise #7

−13⋅4:−8= -13\cdot4:-8=

Video Solution

Step-by-Step Solution

Let's solve the exercise from left to right.

Note that we are first multiplying a negative number by a positive number, therefore the result must be a negative number:

−13×4=−52 -13\times4=-52

Now we got the exercise:

−52:−8= -52:-8=

Let's write the exercise as a simple fraction:

−52−8= \frac{-52}{-8}=

Note that we are dividing between two negative numbers, therefore the result must be a positive number:

528= \frac{52}{8}=

Let's convert it to an addition exercise:

6+48= 6+\frac{4}{8}=

Let's break down the 8 into a multiplication exercise:

6+44×2= 6+\frac{4}{4\times2}=

Let's reduce the 4 in both eight and the fraction's denominator:

6+12=612 6+\frac{1}{2}=6\frac{1}{2}

Answer

612 6\frac{1}{2}

Exercise #8

200:−200⋅200= 200:-200\cdot200=

Video Solution

Step-by-Step Solution

Let's solve the exercise from left to right.

First, we'll write the division problem in the form of a fraction:

200−200×200= \frac{200}{-200}\times200=

We should note that we are dividing a positive number by a negative number, so the result will necessarily be a negative number:

−200200×200= -\frac{200}{200}\times200=

Let's simplify the 200 and we get:

−200 -200

Answer

−200 -200

Exercise #9

−81:−27⋅6:−2= -81:-27\cdot6:-2=

Video Solution

Step-by-Step Solution

Let's write the exercise as a multiplication of fractions:

(−81:−27)×(6:−2)= (-81:-27)\times(6:-2)=

−81−27×6−2= \frac{-81}{-27}\times\frac{6}{-2}=

Note that in the first fraction we are dividing between two negative numbers, therefore the result must be a positive number.

Note that in the second fraction we are dividing between a positive number and a negative number, therefore the result must be a negative number.

Therefore:

8127×−62= \frac{81}{27}\times-\frac{6}{2}=

Let's break down 81 into a multiplication exercise and 6 into a multiplication exercise:

27×327×−2×32= \frac{27\times3}{27}\times-\frac{2\times3}{2}=

Let's reduce the 27 and the 2 in the numerator and denominator of the fraction and we get:

3×−3= 3\times-3=

Note that we are multiplying between a positive number and a negative number, therefore the result must be a negative number:

−9 -9

Answer

−9 -9

Exercise #10

Solve the following problem:

−5⋅−49:14⋅−10= -5\cdot-49:14\cdot-10=

Video Solution

Step-by-Step Solution

Let's write the exercise in the following way:

−5×−4914×−10= \frac{-5\times-49}{14}\times-10=

Note that in the numerator of the fraction we are multiplying two negative numbers, therefore the result must be a positive number:

5×4914×−10= \frac{5\times49}{14}\times-10=

Break down 49 and 14 into multiplication exercises:

5×7×77×2×−10= \frac{5\times7\times7}{7\times2}\times-10=

Reduce the 7 in the numerator and denominator of the fraction and proceed to break down the 10 into a multiplication exercise:

5×72×−5×2= \frac{5\times7}{2}\times-5\times2=

Reduce the 2 and note that we are multiplying a positive number by a negative number, therefore the result must be negative:

−5×7×5= -5\times7\times5=

Let's solve the exercise from left to right.

Note that first we are multiplying a negative number by a positive number, therefore the result must be a negative number:

−5×7=−35 -5\times7=-35

We obtain the following:

−35×5= -35\times5=

Note that we are multiplying a negative number by a positive number, therefore the result must be a negative number:

−175 -175

Answer

−175 -175

Exercise #11

−7:−49:+14:(−3+2)= -7:-49:+14:(-3+2)=

Video Solution

Step-by-Step Solution

First, let's solve what's inside the parentheses:

−3+2=−1 -3+2=-1

Now the exercise looks like this:

−7:−49:+14:−1= -7:-49:+14:-1=

Let's treat the exercise as division between two simple fractions:

(−7:−49):(+14:−1)= (-7:-49):(+14:-1)=

−7−49:+14−1= \frac{-7}{-49}:\frac{+14}{-1}=

Let's look at the simple fraction on the left side.

Since we are dividing a negative number by a negative number, the result will be positive.

Let's break down 49 into a multiplication exercise:

77×7= \frac{7}{7\times7}=

Let's reduce the 7 in the numerator and denominator and we get:

17 \frac{1}{7}

Now the exercise we got is:

17:+14−1= \frac{1}{7}:\frac{+14}{-1}=

Let's convert the division to multiplication, don't forget to switch between numerator and denominator:

17×−1+14= \frac{1}{7}\times\frac{-1}{+14}=

Let's reduce to one exercise:

1×−17×14=−1+98 \frac{1\times-1}{7\times14}=\frac{-1}{+98}

Since we are dividing a negative number by a positive number, the result will be negative:

−:+=− -:+=-

Therefore we get:

−198 -\frac{1}{98}

Answer

−198 -\frac{1}{98}

Exercise #12

+400⋅(−4):−16:−6= +400\cdot(-4):-16:-6=

Video Solution

Step-by-Step Solution

Let's write the exercise in the following form:

400×(−4)−16:−6= \frac{400\times(-4)}{-16}:-6=

Let's factor -16 in the denominator as a multiplication exercise:

400×(−4)4×(−4):−6= \frac{400\times(-4)}{4\times(-4)}:-6=

Let's reduce -4 in both the numerator and denominator and get:

4004:−6= \frac{400}{4}:-6=

Let's factor the 100 in the numerator as a multiplication exercise:

100×44:−6= \frac{100\times4}{4}:-6=

Let's reduce the 4 in both the numerator and denominator and get:

100:−6= 100:-6=

Let's write the exercise as a fraction:

100−6= \frac{100}{-6}=

Note that we are dividing a positive number by a negative number, therefore the result must be negative.

Let's factor the 100 as an addition exercise:

−96+46= -\frac{96+4}{6}=

Let's write the exercise in the following way:

−(966+46)= -(\frac{96}{6}+\frac{4}{6})=

Let's solve the first fraction and in the second fraction let's factor the numerator and denominator as multiplication exercises:

−(16+2×22×3)= -(16+\frac{2\times2}{2\times3})=

Let's reduce the 2 in both the numerator and denominator:

−(16+23)= -(16+\frac{2}{3})=

Let's pay attention to the appropriate sign since we are multiplying by a negative number:

−1623 -16\frac{2}{3}

Answer

−1623 -16\frac{2}{3}

Exercise #13

−3⋅8:0⋅−14= -3\cdot8:0\cdot-14=

Video Solution

Step-by-Step Solution

Let's begin by rewriting the exercise as follows:

−3×80×−14= \frac{-3\times8}{0}\times-14=

One should consider that it's not possible to divide a number by zero thus the expression has no meaning.

Answer

There is no meaning to the expression