Tag: decimal numbers

Questions Related to decimal numbers

The simplified value of $\displaystyle\frac{10.24 \div 1.6}{20 - 19.8}$ is

  1. $1.6$

  2. $3.2$

  3. $16$

  4. $32$


Correct Option: D
Explanation:

$\displaystyle\frac { 10.24 }{ 1.6 } = \displaystyle\frac { 102.4 }{ 16 } = 6.4$
$\therefore \displaystyle\frac { 10.24\div 1.6 }{ 20-19.8 } = \displaystyle\frac { 6.4 }{ 0.2 } = \displaystyle\frac { 64 }{ 2 } = 32$

Simplify :$\displaystyle \left ( 0.\overline{1} \right )^{2}\left { 1-9\left ( 0.\overline{16} \right )^{2} \right }$

  1. $\displaystyle \frac{1}{162}$

  2. $\displaystyle \frac{1}{108}$

  3. $\displaystyle \frac{7696}{10{6}}$

  4. $\displaystyle \frac{1}{106}$


Correct Option: B
Explanation:

$\displaystyle \left ( 0.\overline{1} \right )^{2}\left { 1-9\left ( 0.\overline{16} \right )^{2} \right }$


= $\displaystyle \left ( \frac{1}{9} \right )^{2}\left { 1-9\left ( \frac{16-1}{90} \right )^{2} \right }=\frac{1}{81}\left { 1-9\times\left ( \frac{15}{90} \right )^{2}  \right }$

= $\displaystyle \frac{1}{81}\left { 1-9\times \frac{1}{36} \right }=\frac{1}{81}\times \frac{3}{4}=\frac{1}{108}$

Simplify : $[ 0.9 - { 2.3 - 3.2 - 3.2 - ( 7.1- 5.4 - 3.5 ) } ]$

  1. 0.18

  2. 1.8

  3. 0

  4. 2.6


Correct Option: C
Explanation:

$\displaystyle \left [ 0.9-\left { 2.3-3.2-\left ( 7.1-5.4-3.5 \right ) \right } \right ]$


=$\displaystyle \left [ 0.9-\left { 2.3-3.2-\left ( 7.1-8.9 \right ) \right } \right ]$

= $\displaystyle \left [ 0.9-\left { 2.3-3.2-\left ( -1.8 \right ) \right } \right ]$

= $\displaystyle \left [ 0.9-\left { 2.3-3.2+1.8 \right } \right ]$

= $\displaystyle \left [ 0.9-\left { 4.1-3.2 \right } \right ]$

= $\displaystyle \left [ 0.9-0.9 \right ]=0 $

$\displaystyle (0.34\overline{67}+0.13\overline{33})$ is equal to 

  1. $\displaystyle 0.\overline{48}$

  2. 0.4803

  3. $\displaystyle 0.48\overline{01}$

  4. $\displaystyle 0.4\overline{8}$


Correct Option: C
Explanation:

$\displaystyle 0.34\overline{67}+0.13\overline{33}=\frac{3467-34}{9900}+\frac{1333-13}{9900}$


= $\displaystyle \frac{3433}{9900}+\frac{1320}{9900}=\frac{4753}{9900}$

= $\displaystyle \frac{4801-48}{9900}=0.4801 $

Evaluate the expression $\displaystyle 6\frac{1}{4}\times 0.25+0.75-0.3125$

  1. $5.9375$

  2. $4.2968$

  3. $2.1250$

  4. $2$


Correct Option: D
Explanation:

$\displaystyle 6\frac{1}{4}\times 0.25+0.75-0.3125$
$= 6.25 \times 0.25 + 0.75 - 0.3125$
$= 1.5625 + 0.75 - 0.3125$
$= 2.3125 - 0.3125 = 2$

The value of $\displaystyle 0.\overline{2}+0.\overline{3}+0.\overline{4}+0.\overline{9}+0.\overline{39}$ is 

  1. $\displaystyle 0.\overline{57}$

  2. $\displaystyle 1\frac{20}{33}$

  3. $\displaystyle 2\frac{1}{3}$

  4. $\displaystyle 2\frac{13}{33}$


Correct Option: D
Explanation:

$\displaystyle 0.\overline{2}+0.\overline{3}+0.\overline{4}+0.\overline{9}+0.\overline{39}$


= $\displaystyle \frac{2}{9}+\frac{3}{9}+\frac{4}{9}+\frac{9}{9}+\frac{39}{99}$

= $\displaystyle \frac{22+33+44+99+39}{99}$

= $\displaystyle \frac{237}{99}=2\frac{13}{33}$

Simplify $\displaystyle :0.\overline{4}+0.\overline{61}+0.\overline{11}-0.\overline{36}$

  1. $\displaystyle 0.\overline{83}$

  2. $\displaystyle 0.\overline{87}$

  3. $\displaystyle 0.\overline{80}$

  4. $\displaystyle 0.\overline{85}$


Correct Option: C
Explanation:

$\displaystyle :0.\overline{4}+0.\overline{61}+0.\overline{11}-0.\overline{36}=\frac{4}{9}+\frac{61}{99}+\frac{11}{99}-\frac{36}{99}=\frac{4}{9}+\frac{72}{99}-\frac{36}{99}$


$\displaystyle=\frac{4}{9}+\frac{36}{99}=\frac{44}{99}+\frac{36}{99}=\frac{80}{99}=0.\overline{80}$

In a number system the product of 44 and 11 is 3414 The number 3111 of this system when converted to the decimal number system becomes

  1. 406

  2. 1086

  3. 213

  4. 691


Correct Option: A
Explanation:

The product of 44 and 11 is 484
If base is x then 3411
$3x^3+4x^2+1x^1+4x^0=484$
$3x^3+4x^2+x=480$
This equation is satisfy when x=5
then base is 5
In decimal system number 3111 will be  written
$3\times 5^3+1\times 5^2+1\times 5^1+1\times 5^0=406$

A mathematician born in the first half of the 19th century was x years old in the year $x^2$. He was born in

  1. 1849

  2. 1806

  3. 1812

  4. 1852


Correct Option: B
Explanation:

The man born between $1800$ and $1850$ which is a perfect square. 
The perfect square number is $43 = 1849$ (Since$ 42 = 1764$ and $44 = 1936$ ) 
So in the year $1849$ the man was $43$ years old. 
Which shows the year of born is $1849 - 43 = 1806.$

$\displaystyle 8.8 =6+\frac {7} {?} $

Find $?$

  1. $2.5$

  2. $2.8$

  3. $2.2$

  4. None of these


Correct Option: A
Explanation:
Let $?$ be x
$8.8=6+\dfrac{7}{x}$

$8.8-6=\dfrac{7}{x}$

$\dfrac{7}{x}=2.8$

$\dfrac{7}{2.8}=x$

$x=\dfrac{5}{2}$

$x=2.5$
Hence option A is correct.