Tag: ways to multiply and divide

Questions Related to ways to multiply and divide

72 $\times $ b = 4572a then the value of a + b is (where a is a single digit whole number and b is a natural number)

  1. 635

  2. 471

  3. 640

  4. None of these


Correct Option: A

Which natural number is nearest to $9217$, which is completely divisible by $88$ ?

  1. $9152$

  2. $9240$

  3. $9064$

  4. $9184$


Correct Option: B
Explanation:

On dividing we get,
$\frac { 9217 }{ 88 } =104\frac { 65 }{ 88 } $

Therefore,

Required number 

$= 9217 + (88 - 65)$ ,Because (88 - 65) < 65.

$= 9217 + 23$

$= 9240$

Find the value of A and B in the following sum:
$3 B$
$\underline {\times A}$
$\underline {2 5 2}$

  1. $B=6,A=7$

  2. $B=4,A=3$

  3. $B=3,A=4$

  4. $B=7,A=6$


Correct Option: A
Explanation:

Now as $A \times B$ gives 2 in the product, the combinations could be

$2\times 1$ or $1 \times 2, 6 \times 2$ or $2\times 6, 3 \times 4$

or $4 \times 3, 6 \times 7$ or $7 \times 6$ or $8 \times 4$ or

$4\times 8, 9 \times 8$ or $8\times 9$. But to get 2 in hundred's

place and 5 in ten's place in the product, B has to be 6 and A has to be

7. Then $6\times 7=42$.
Write 2 and carry over 4. then $7\times 3= 21$ and add 4 to get 2 and 5 in the product.
The value of B is 6 and A is 7.

The least number which on division by 35 leaves a remainder 25 and on division by 45 leaves the remainder 35 and on division by 55 leaves the remainder of 45 is

  1. 2515

  2. 3455

  3. 2875

  4. 2785


Correct Option: B
Explanation:

$35=5\times7$
$45=3\times3\times5$
$55=5\times11$
LCM of (35,45,55)=$3\times3\times5\times\times7\times11=3465$
Since difference between divisor and remainder is 10
Hence least number is $3465-10=3455$

An integer is multiplied by 2 and the result is then multiplied by 5 The final result could be

  1. 64

  2. 32

  3. 12

  4. 30


Correct Option: D
Explanation:

If a number is multiplied by 2 and 5 respectively. Then number should be divided by their L.C.M i.e  by 10.
Clearly, only number divisible by 10 is 30.
Hence, option D is correct.

If $\displaystyle a=(2^{-2}-2^{-3}),b=(2^{-3}-2^{-4})and: c=(2^{-4}-2^{-2})$ then find the value of 3 abc

  1. $\displaystyle \frac{-63}{1024}$

  2. $\displaystyle \frac{-63}{2048}$

  3. $\displaystyle \frac{-9}{2048}$

  4. $\displaystyle \frac{9}{1024}$


Correct Option: C
Explanation:

$a=(2^{-2}-2^{-3}),b=(2^{-3}-2^{-4})and: c=(2^{-4}-2^{-2})$
So,  $3abc=3\times (2^{ -2 }-2^{ -3 })\times (2^{ -3 }-2^{ -4 })\times (2^{ -4 }-2^{ -2 })$
$3abc=3\times (1/4-1/8)\times (1/8-1/16)\times (1/16-1/4)$
$3abc=3\times (1/8)\times (1/16)\times (-3/16)$
$3abc=\frac { -9 }{ 2048 } $
Answer (C) $\displaystyle \frac{-9}{2048}$

Simplify : $\displaystyle\frac{9^{5/2}-3\times7^0-\begin{pmatrix}\displaystyle\frac{1}{81}\end{pmatrix}^{-\displaystyle\frac{1}{2}}}{(27)^{2/3}-\begin{pmatrix}\displaystyle\frac{8}{27}\end{pmatrix}^{2/3}}$

  1. $0$

  2. $16$

  3. $27$

  4. $77$


Correct Option: C
Explanation:

$
\frac { { 9 }^{ \frac { 5 }{ 2 }  }-{ 3\times 7 }^{ 0 }{ \quad -\frac { 1 }{ 81 }  }^{ -\frac { 1 }{ 2 }  } }{ { 27 }^{ \frac { 2 }{ 3 }  }-(\frac { 8 }{ 27 } )^{ \frac { 2 }{ 3 }  } } \quad \quad \ \ NR\quad =\quad { 3 }^{ 2\times \frac { 5 }{ 2 }  }-3-(\frac { 1 }{ 81 } )^{ -\frac { 1 }{ 2 }  }\quad =\quad { 3 }^{ 5 }-3-({ 3 }^{ -4\times \frac { -1 }{ 2 }  })\quad =243-3-9=\quad 231\quad \ Dr\quad =\quad { 3 }^{ 3\times \frac { 2 }{ 3 }  }-(\frac { 2 }{ 3 } )^{ 3\times \frac { 2 }{ 3 }  }\quad =\quad 9\quad -\quad \frac { 4 }{ 9 } \quad =\quad 77/9\ \frac { Dr }{ Nr } \quad =\quad \frac { 231 }{ 77/9 } \quad =\quad 3\times 9\quad =\quad 27
$

If $\div$ means $-$, $-$ means $\times$, $\times$ means $+$ and $+$ means $\div$, then
$20\times 60\div 40-20+10=$

  1. $40$

  2. $0$

  3. $80$

  4. $60$


Correct Option: B
Explanation:

$20\times 60\div 40-20+10=$
After putting the true sign, we get
$20+ 60- 40\times20\div10=$
$20+60-80=$
$0=0$
Answer (B) 0

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 ______ .

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

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

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

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


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?

  1. $125$ people

  2. $50$ people

  3. $18$ people

  4. $32$ people


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