Tag: decimal fractions

Questions Related to decimal fractions

0.585 is equal to

  1. $\frac{589}{100}$

  2. $\frac{585}{1000}$

  3. $\frac{1000}{585}$

  4. None of these


Correct Option: B
Explanation:

$0.585 = 0.5+0.08+0.005 = \dfrac{5}{10} + \dfrac{8}{100} + \dfrac{5}{1000}$
$0.585 = \dfrac{585}{1000}$

$0.2008$ is equal to

  1. $\dfrac {252}{1250}$

  2. $\dfrac {251}{1250}$

  3. $\dfrac {250}{1250}$

  4. None of these


Correct Option: B
Explanation:

$\dfrac {2008}{1000} = \dfrac {1004}{500}$


$= \dfrac {502}{250}$$= \dfrac {251}{125}$

So, option $B$ is correct.

Convert the following into a fraction:

$0.2\times 0.02\times 0.002$

  1. $\dfrac {1}{125}$

  2. $\dfrac {1}{1250}$

  3. $\dfrac {1}{125000}$

  4. None of these


Correct Option: C
Explanation:

$\dfrac {2}{10}\times \dfrac {2}{100} \times \dfrac {2}{1000}$

$= \dfrac {8}{10\times 100\times 1000}$

$= \dfrac {4}{5\times 100\times 1000}$

$= \dfrac {1}{125000}$

So, option $C$ is correct.

$2.\overline{8768}$  expressed as a rational number is 

  1. $\displaystyle 2\frac{878}{999}$

  2. $\displaystyle 2 _{10}^{9}$

  3. $\displaystyle 2\frac{292}{333}$

  4. $\displaystyle 2\frac{4394}{4995}$


Correct Option: C
Explanation:

$\displaystyle 2.\overline{8768}=2+0.\overline{8768}$
= $\displaystyle 2+\frac{8768-8}{9990}=2+\frac{8760}{9990}$
= $\displaystyle 2+\frac{292}{333}=2\frac{292}{333}$

Express the following as a fraction and simplify:

$2.45$

  1. $\cfrac {49}{20}$

  2. $\cfrac {20}{49}$

  3. $\cfrac {19}{20}$

  4. $\cfrac {20}{19}$


Correct Option: A
Explanation:

To convert a decimal to a fraction, write it over the appropriate power of 10 and simplify:
$2.45 = 2\cfrac{45}{100} = 2\cfrac{9}{20}$    ...Mixed fraction

$=\cfrac{49}{20}$     ....Improper fraction

The decimal number $53.234$ is a rational number whose denominator is ............

  1. $100000$

  2. $10000$

  3. $1000$

  4. $100$


Correct Option: C
Explanation:

$53.234 = \dfrac {53234}{1000} = \dfrac {53234}{10^{3}}$
Denominator is $1000$.
Therefore, $C$ is the correct answer.

Express the infinite decimal .212121 as a common fraction.

  1. $\frac{21}{100}$

  2. $\frac{23}{99}$

  3. $\frac{7}{100}$

  4. $\frac{7}{99}$

  5. $\frac{7}{33}$


Correct Option: E
Explanation:

$Let\quad x=0.212121...\ 100x=21.212121....\ 100x-x=21\ 99x=21\ x=\frac { 21 }{ 99 } =\frac { 7 }{ 33 } $

So correct answer will be option E

Write the number of significant digits in:

$3.005$.

  1. $4$

  2. $2$

  3. $1$

  4. $0$


Correct Option: A
Explanation:

Zeroes placed between other digits are always significant.
$\therefore  3.005$ has $4$ significant digits.

Write the number of significant digits in:

$5.16 \times 10^8$.

  1. $3$

  2. $1$

  3. $2$

  4. $9$


Correct Option: A
Explanation:

$5.16\times 10^8$
There are $3$ significant figures. When a number is  written in scientific notation, only significant figures are placed into the numerical portion.


Write the number of significant digits in:

$16.000$.

  1. $2$

  2. $5$

  3. $16$

  4. $1$


Correct Option: B
Explanation:

All zeroes which are both to the right of the decimal point and to the right of all non-zero significant digits are themselves significant.
$\therefore  16.000$ has $5$
significant digits