Tag: maths

Questions Related to maths

If $\displaystyle 15\frac {2}{3}\times 3\frac {1}{6}+6\frac {1}{3}=11\frac {7}{18}+x$, then the value of $x$ is ______ .

maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

  1. $\displaystyle 39\frac {5}{9}$

  2. $\displaystyle 137\frac {4}{9}$

  3. $\displaystyle 29\frac {7}{9}$

  4. $\displaystyle 44\frac {5}{9}$

Show answer
Correct Option: D
Explanation:

$15\frac{2}{3}\times 3\frac{1}{6}+6\frac{1}{3}= 11\frac{7}{18}+x$
Or $\frac{47}{3}\times \frac{19}{6}+\frac{19}{3}= \frac{205}{18}+x$
Or $\frac{893}{18}+\frac{19}{3}= \frac{205}{18}+x$
Or 893+114=205+18x
Or 18x=893+114-205=$\frac{802}{18}=44\frac{5}{9}$

There were $50$ people at the birthday party. John invited $125$ people. Among those who attended, only $36\%$ brought gifts. How many guests brought gifts?

maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

  1. $125$ people

  2. $50$ people

  3. $18$ people

  4. $32$ people

Show answer
Correct Option: C
Explanation:

Invited people=125
people attended birthday party=50
As per question, 36% brought gifts
$G=50\times \frac { 36 }{ 100 } $
$G=18$
Answer (C) 18

The value of $\displaystyle\frac{2^{n+4}-2\times2^{n}}{2\times2^{(n+3)}}+2^{-3}$ is equal to ........... 

maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

  1. $2^{n+1}$

  2. $\begin{pmatrix}\displaystyle\frac{9}{8}-2^{n}\end{pmatrix}$

  3. $\begin{pmatrix}-2^{n+1}+\displaystyle\frac{1}{8}\end{pmatrix}$

  4. $1$

Show answer
Correct Option: D
Explanation:

$\displaystyle\frac{2^{n+4}-2\times2^{n}}{2\times2^{(n+3)}}+2^{-3}$
$\frac { 2^{ n+4 }-2^{ n+1 } }{ 2^{ (n+4) } } +2^{ -3 }$
$\frac { 2^{ n }(2^{ 4 }-2^{ 1 }) }{ 2^{ n }\times { 2 }^{ 4 } } +2^{ -3 }$
$\frac { (2^{ 4 }-2^{ 1 }) }{ { 2 }^{ 4 } } +2^{ -3 }$
$\frac { (16-2) }{ 16 } +\frac { 1 }{ 8 } $
$\frac { 14 }{ 16 } +\frac { 1 }{ 8 } $
$\frac { 14+2 }{ 16 } =1$
Answer (D) 1


Tony needs to solve the equation given below.
$\displaystyle  \frac {3}{4}t=\frac {6}{20}$
What operation should Tony perform to solve the equation for $t$ ?

maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

  1. Multiply both sides by $\displaystyle \frac {1}{4}$

  2. Divide both sides by $\displaystyle \frac {3}{4}$

  3. Add $\displaystyle \frac {3}{4}$ to both sides

  4. Subtract $\displaystyle \frac {3}{4}$ from both sides

Show answer
Correct Option: B
Explanation:

As t term is 3t/4,So to find t we need to divide is by 3/4.
Answer (B) Divide both sides by 3/4

A cricketer whose bowling average is 12.4 runs per wicket takes 5 wickets for 26 runs and thereby decreases his average by 0.4. The number of wickets taken by him till the last match was........

maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

  1. 64

  2. 72

  3. 80

  4. 85

Show answer
Correct Option: D
Explanation:

average = 12.4 runs per wicket, 
Let's assume total  number of wickets taken by him till the last match=x
 total  number of runs taken by him till the last match=y
$y/x=12.4$
$y=12.4x
$(y+26)/(x+5)=12$
$12.4x+26=12x+60$
$0.4x=34$
$x=85$
The number of wickets taken by him till the last match =85
Answer (D) 85

If $4m = 5K$ and $6n = 7K$, the ratio of $m$ to $n$ is

maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

  1. 5:7

  2. 10:21

  3. 14:15

  4. 2:3

  5. 15:14

Show answer
Correct Option: E
Explanation:

Given that $4m=5K$ and $6n=7K$
Now divide those two equations, we get $\dfrac { 4m }{ 6n } =\dfrac { 5K }{ 7K } $
Which gives $ \dfrac { m }{ n } =\dfrac { 5 }{ 7 } \times \dfrac { 6 }{ 4 } =\dfrac { 15 }{ 14 } $

Multiply: $(3 i)(4 + 3i)(5 2i)$

maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

  1. $63-2i$

  2. $23-7i$

  3. $45-6i$

  4. $85-5i$

Show answer
Correct Option: D
Explanation:

$3i\left( 4+3i \right) \left( 52i \right) \ =\quad 156{ i }^{ 2 }\left( 4+3i \right) \ =\quad -156\left( 4+3i \right) \ =\quad -624-468i$


Find : $43245\times 0$

maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

  1. $43245$

  2. $0$

  3. $432450$

  4. $4324$

Show answer
Correct Option: B
Explanation:

We know that any number multiplied by $0$ will always result in $0$. For example: The equation $0\times 2 = 0$ can be read as 'Zero times Two equals Zero'. That means, you are taking $'2'$ zero times, effectively taking nothing. So, multiplying any number by zero will always be zero.


Hence, $43245\times 0=0$.

Which of the following statements do not accurately describe the multiplicative inverse ?

maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

  1. If a given fraction with numerator $1$ , the multiplicative inverse will be its denominator.

  2. If a given whole number the multiplicative inverse will a fraction containing that number as numerator and $1$ as denominator.

  3. In a statement $\sqrt3\times x=1$ , $x$ is the multiplicative inverse.

  4. One pair of number when multiplied together gives the number $1$

Show answer
Correct Option: B
Explanation:

Option $B$ is correct.
The multiplicative inverse will include $1$ as numerator.

Find : $5436\times 1$.

maths ways to multiply and divide mental multiplication multiplication methods multiplication of numbers

  1. $5436$

  2. $0$

  3. $1$

  4. $5437$

Show answer
Correct Option: A
Explanation:

We know that any number multiplied by $1$ will always result in that number itself. For example: The equation $2\times 1 = 2$ can be read as 'two times one equals one'. That means, you are taking $'2'$ one times, effectively taking nothing but multiplying by its unity. So, multiplying any number by one will always be the number itself.


Hence, $5436\times 1=5436$.