Tag: multiplying decimals

Questions Related to multiplying decimals

$5.25\times 9.1\times 0.0\times 8.26=$ ____________.

maths decimal fraction multiplying decimals multiplication of decimals multiplication of division of decimal fraction by whole number and decimal fraction

  1. $47.775$

  2. $0.1176$

  3. $0$

  4. $1$

Show answer
Correct Option: C
Explanation:

The value of $5.25\times 9.1\times 0.0\times 8.26$ is

$(47.775)\times (0)$
$=0$

The value of $\dfrac{0.008\times 0.01\times 0.0072}{(0.12\times 0.0004)}$ is:

maths decimal fraction multiplying decimals multiplication of decimals multiplication of division of decimal fraction by whole number and decimal fraction

  1. $0.012$

  2. $0.12$

  3. $1.02$

  4. $1.2$

Show answer
Correct Option: A
Explanation:

Given expression 


$\dfrac{0.008\times 0.01\times 0.0072}{(0.12\times 0.0004)}$ 

$=\dfrac {0.008\times0.01\times0.0072}{0.000048}$

$=0.00008\times\dfrac{0.0072}{0.000048}$

$=\dfrac{8}{48}\times\dfrac{72}{1000}$

$=0.012$

Find the value of following expression:
$\dfrac{(0.1667)(0.8333)(0.3333)}{(0.2222)(0.6667)(0.1250)}$

maths decimal fraction multiplying decimals multiplication of decimals multiplication of division of decimal fraction by whole number and decimal fraction

  1. $2$

  2. $2.40$

  3. $2.43$

  4. $2.50$

  5. $None\ of\ these$

Show answer
Correct Option: A

Number of zero's in the product of
$5 \times 10 \times 25 \times 40 \times 50 \times 55 \times 65 \times 125 \times 80 $

maths decimal fraction multiplying decimals multiplication of decimals multiplication of division of decimal fraction by whole number and decimal fraction

  1. $8$

  2. $9$

  3. $12$

  4. $13$

Show answer
Correct Option: B
Explanation:

$5 \times 10 \times 25 \times 40 \times 50 \times 55 \times 65 \times 125 \times 80 $
$= 5 \times 2 \times 5 \times 5^2 \times 2^3 \times 5 \times 2 \times 5^2 \times 11 \times 5 \times 13 \times 5 \times 5^3 \times 2^4 \times 5$
$= 2^9 \times 5^{13}\times 11 \times 13 = (2 \times 5)^9 \times 5^4 \times 11 \times 13$


As we know that zeroes are formed by the product of a $2$ and a $5$ i.e. $2$ x $5$. 

Therefore, number of zeroes depends on the number of pairs of $2$'s and $5$'s that can be formed in the given product. 

Since $9$ pairs of $2$'s and $5$'s are formed in the given product, hence there will be $9$ zeroes in the given product.

If u, v and w are the digits of decimal system, then the rational number represented by 0.uwuvuvuvuv......is

maths decimal fraction multiplying decimals multiplication of decimals multiplication of division of decimal fraction by whole number and decimal fraction

  1. (100 uw + 99 uv)/99

  2. (99uw + uv)/980

  3. (99uw + uv)/9900

  4. (9uw + 99uv)/900

Show answer
Correct Option: C
Explanation:

x =0.uwuvuvuvuv...
x = O.uwuv
(i) x 100
100x = uw. uv
(ii) x 100
10000x = uwuv - uv
(iii) - (ii)

Each piece of cardboard is $0.3\ cm$ thick. If Marie stacks $8$ pieces of cardboard on top of one another, how thick will the stack be?

maths decimal fraction multiplying decimals multiplication of decimals multiplication of division of decimal fraction by whole number and decimal fraction

  1. $2.4\ cm$

  2. $24\ cm$

  3. $2.1\ cm$

  4. $21\ cm$

Show answer
Correct Option: A
Explanation:

It is given that each piece of cardboard is $0.3$ cm thick which means that one piece is $0.3$ cm thick.


If Marie stacks $8$ pieces of cardboard, then the thickness of $8$ pieces of cardboard will be:

$0.3\times 8=2.4$ cm

Hence, the stack will be $2.4$ cm thick.

If $100\times \text{ ? }=352$. Then, find the missing number.

maths decimal fraction multiplying decimals multiplication of decimals multiplication of division of decimal fraction by whole number and decimal fraction

  1. $0.352$

  2. $352$

  3. $35.2$

  4. $3.52$

Show answer
Correct Option: D
Explanation:

Let $x$ be the missing number.


$100\times x=352\ \Rightarrow 100x=352\ \Rightarrow x=\dfrac { 352 }{ 100 } \ \Rightarrow x=352\times 0.01\quad \quad \quad \quad \quad \left{ \because \quad \dfrac { 1 }{ 10 } =0.1,\dfrac { 1 }{ 100 } =0.01,.... \right} \ \Rightarrow x=3.52$

Hence, the missing number is $3.52$.

Calculate $456.78\times 8$.

maths decimal fraction multiplying decimals multiplication of decimals multiplication of division of decimal fraction by whole number and decimal fraction

  1. $36542.4$

  2. $365.424$

  3. $3,654.24$

  4. $36.5424$

Show answer
Correct Option: C
Explanation:
Let us first multiply the two given numbers $456.78$ and $8$ without decimal point:

$45678\times 8=365424$

Since, $456.78$ has two decimal places, therefore the answer $365424$ should also have two decimal places that is $3654.24$.

Hence, $456.78\times 8=3,654.24$.

$45.678\times \text{ ? }=1187.628$. Find $?$.

maths decimal fraction multiplying decimals multiplication of decimals multiplication of division of decimal fraction by whole number and decimal fraction

  1. $26$

  2. $27$

  3. $28$

  4. $29$

Show answer
Correct Option: A
Explanation:

Let $x$ be the missing number.


$45.678\times x=1187.628\ \Rightarrow 45.678x=1187.628\ \Rightarrow \dfrac { 45678x }{ 1000 } =\dfrac { 1187628 }{ 1000 } \quad \quad \quad \quad \quad \left{ \because \quad \dfrac { 1 }{ 10 } =0.1,\dfrac { 1 }{ 100 } =0.01,.... \right} \ \Rightarrow x=\dfrac { 1187628 }{ 1000 } \times \dfrac { 1000 }{ 45678 } \ \Rightarrow x=26$

Hence, the missing number is $26$.

Multiply $43.09$ with $23$.

maths decimal fraction multiplying decimals multiplication of decimals multiplication of division of decimal fraction by whole number and decimal fraction

  1. $99.107$

  2. $991.07$

  3. $9910.7$

  4. $9.9107$

Show answer
Correct Option: B
Explanation:
Let us first multiply the two given numbers $43.09$ and $23$ without decimal point:
$4309\times 23=99107$
Since, $43.09$ has two decimal places, therefore the answer $99107$ should also have two decimal places that is $991.07$.
Hence, $43.09\times 23=991.07$.