Examples with solutions for Multiplication and Division of Signed Mumbers: Using fractions

Exercise #1

Solve the following expression:

(+7)×(+156)= (+7)\times(+1\frac{5}{6})=

Video Solution

Step-by-Step Solution

Let's convert the mixed fraction to an improper fraction:

156=116 1\frac{5}{6}=\frac{11}{6}

Now let's write the exercise:

7×116=71×116= 7\times\frac{11}{6}=\frac{7}{1}\times\frac{11}{6}=

We'll multiply numerator by numerator and denominator by denominator:

7×111×6=776 \frac{7\times11}{1\times6}=\frac{77}{6}

Let's convert the improper fraction to a mixed fraction:

776=1256 \frac{77}{6}=12\frac{5}{6}

Answer

1256 12\frac{5}{6}

Exercise #2

−723:0= ? -\frac{72}{3}:0=\text{ ?}

Video Solution

Step-by-Step Solution

Let's write the expression in the form of a simple fraction:

−7230 \frac{-\frac{72}{3}}{0}

Since it is not possible to divide a number by 0, the expression is invalid.

Answer

The expression is invalid.

Exercise #3

+12:+4= +\frac{1}{2}:+4=

Video Solution

Step-by-Step Solution

Let's convert 4 to a simple fraction:

4=41 4=\frac{4}{1}

Now the exercise we received is:

12:41= \frac{1}{2}:\frac{4}{1}=

Let's convert the division exercise to a multiplication exercise, and don't forget to switch the numerator and denominator in the second fraction:

12×14= \frac{1}{2}\times\frac{1}{4}=

We'll combine it into one multiplication exercise and solve:

1×12×4=18 \frac{1\times1}{2\times4}=\frac{1}{8}

Answer

18 \frac{1}{8}

Exercise #4

+217:+14= ? +2\frac{1}{7}:+\frac{1}{4}=\text{ ?}

Video Solution

Step-by-Step Solution

Let's first convert 2 and seven-sevenths into a simple fraction:

217=2+17=2×77+17=2×77+17=147+17=14+17=157 2\frac{1}{7}=2+\frac{1}{7}=2\times\frac{7}{7}+\frac{1}{7}=\frac{2\times7}{7}+\frac{1}{7}=\frac{14}{7}+\frac{1}{7}=\frac{14+1}{7}=\frac{15}{7}

Now the exercise we have is:

157:14= \frac{15}{7}:\frac{1}{4}=

next we convert the division exercise into a multiplication exercise, remembering to switch the numerator and denominator in the second fraction:

157×41= \frac{15}{7}\times\frac{4}{1}=

Let's now combine into one multiplication exercise:

15×47×1=607 \frac{15\times4}{7\times1}=\frac{60}{7}

Next, we factor 60 into an addition exercise:

56+47= \frac{56+4}{7}=

Then let's separate the exercise into addition between fractions:

567+47= \frac{56}{7}+\frac{4}{7}=

Finally, we solve the first fraction exercise to get our answer:

8+47=847 8+\frac{4}{7}=8\frac{4}{7}

Answer

847 8\frac{4}{7}

Exercise #5

+914:+247 +9\frac{1}{4}:+\frac{24}{7}

Video Solution

Step-by-Step Solution

Let's convert 9 and a quarter to a simple fraction:

914=9+14=9×44+14=364+14=36+14=374 9\frac{1}{4}=9+\frac{1}{4}=\frac{9\times4}{4}+\frac{1}{4}=\frac{36}{4}+\frac{1}{4}=\frac{36+1}{4}=\frac{37}{4}

Now the exercise we got is:

374:247= \frac{37}{4}:\frac{24}{7}=

Let's convert the division exercise to a multiplication exercise, and don't forget to switch the numerator and denominator in the second fraction:

374×724= \frac{37}{4}\times\frac{7}{24}=

Let's combine it into one multiplication exercise:

37×724×4=25996 \frac{37\times7}{24\times4}=\frac{259}{96}

Answer

25996 \frac{259}{96}

Exercise #6

Solve the following:

850−1= \frac{850}{-1}=

Step-by-Step Solution

Let's note that we are dividing a positive number by a negative number, and therefore the result will necessarily be a negative number:

+:−=− +:-=-

Let's remember the rule:

x1=x \frac{x}{1}=x

In other words, any number divided by 1 will be equal to itself.

Therefore:

850−1=−850 \frac{850}{-1}=-850

Answer

−850 -850

Exercise #7

Solve the following problem:

(−712):(+1)= (-7\frac{1}{2}):(+1)=

Step-by-Step Solution

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

−:+=− -:+=-

We will write the exercise in the following way:

−7121= \frac{-7\frac{1}{2}}{1}=

Let's remember the rule:

x1=x \frac{x}{1}=x

In other words, any number divided by 1 will be equal to itself.

Therefore, the answer is:

−712 -7\frac{1}{2}

Answer

−712 -7\frac{1}{2}

Exercise #8

Complete the following exercise:

(−12)⋅(−2)= (-\frac{1}{2})\cdot(-2)=

Video Solution

Step-by-Step Solution

Let's recall the rule:

(−x)×(−x)=+x (-x)\times(-x)=+x

Therefore, the sign of the exercise result will be positive:

−12×−2=+1 -\frac{1}{2}\times-2=+1

Answer

1 1

Exercise #9

Solve the following:

60−120= \frac{60}{-120}=

Video Solution

Step-by-Step Solution

To solve the problem 60−120\frac{60}{-120}, follow these steps:

  • Step 1: Find the greatest common divisor (GCD) of 60 and 120. The GCD is 60.
  • Step 2: Simplify the fraction by dividing both the numerator and the denominator by their GCD:

60−120=60÷60−120÷60=1−2 \frac{60}{-120} = \frac{60 \div 60}{-120 \div 60} = \frac{1}{-2}

  • Step 3: When dividing a positive number by a negative number, the result is negative. Thus, 1−2\frac{1}{-2} simplifies to −12-\frac{1}{2}.

Thus, the solution to the problem is −12\boxed{-\frac{1}{2}}.

Answer

−12 -\frac{1}{2}

Exercise #10

Solve the following:

−501= \frac{-50}{1}=

Step-by-Step Solution

Note that we are dividing a negative number by a positive number, and therefore the result will necessarily be a negative number:

−:+=− -:+=-

Let's remember the rule:

x1=x \frac{x}{1}=x

In other words, any number divided by 1 will be equal to itself.

Therefore:

−501=−50 \frac{-50}{1}=-50

Answer

−50 -50

Exercise #11

−47:0= ? -\frac{4}{7}:0=\text{ ?}

Video Solution

Step-by-Step Solution

First let's write the expression in the form of a simple fraction:

−470 \frac{-\frac{4}{7}}{0}

Since it is not possible to divide a number by 0, the expression is invalid.

Answer

The expression is invalid.

Exercise #12

(±3313):(±11213)= ? (\pm3\frac{3}{13}):(\pm1\frac{12}{13})=\text{ ?}

Video Solution

Step-by-Step Solution

Since we are dividing two positive numbers, the result must be a positive number:

+:+=+ +:+=+

First, we'll convert each mixed fraction into an improper fraction as follows:

3313=3×13+313=39+313=4213 3\frac{3}{13}=\frac{3\times13+3}{13}=\frac{39+3}{13}=\frac{42}{13}

11213=1×13+1213=13+1213=2513 1\frac{12}{13}=\frac{1\times13+12}{13}=\frac{13+12}{13}=\frac{25}{13}

Now we have:

4213:2513 \frac{42}{13}:\frac{25}{13}

We'll convert the division problem into multiplication, remembering to switch the numerator and denominator:

4213×1325= \frac{42}{13}\times\frac{13}{25}=

We'll simplify the 13 to get:

4225= \frac{42}{25}=

Now we'll factor 42 into an addition problem:

25+1725=2525+1725= \frac{25+17}{25}=\frac{25}{25}+\frac{17}{25}=

Finally, we will solve accordingly to get:

1+1725=11725 1+\frac{17}{25}=1\frac{17}{25}

Answer

11725 1\frac{17}{25}

Exercise #13

Solve the following expression:

(+45715):(+9)= (+45\frac{7}{15}):(+9)=

Video Solution

Step-by-Step Solution

Since we are dividing two positive numbers, the result must be a positive number:

+:+=+ +:+=+

First, let's convert each mixed fraction to an improper fraction as follows:

9=91 9=\frac{9}{1}

45715=45×15+715= 45\frac{7}{15}=\frac{45\times15+7}{15}=

Let's solve the multiplication in the numerator:

45×15675 45\\\times15\\675

We should obtain the following:

675+715=68215 \frac{675+7}{15}=\frac{682}{15}

Now our division problem between the fractions looks like this:

68215:91= \frac{682}{15}:\frac{9}{1}=

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

68215×19= \frac{682}{15}\times\frac{1}{9}=

Let's combine everything into one problem:

682×115×9= \frac{682\times1}{15\times9}=

Let's solve the problem in the numerator:

15×9135 15\\\times9\\135

And the result is:

682135 \frac{682}{135}

Answer

682135 \frac{682}{135}