Tag: multiplication methods

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Questions Related to multiplication methods

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

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. $B=7,A=6$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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
Reveal answer Fill a bubble to check yourself
B Correct answer
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 $3465-10=3455$

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

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. $\displaystyle \frac{9}{1024}$
Reveal answer Fill a bubble to check yourself
C Correct answer
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) $\displaystyle \frac{-9}{2048}$

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

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. $77$
Reveal answer Fill a bubble to check yourself
C Correct answer
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
$

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

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. $\displaystyle 44\frac {5}{9}$
Reveal answer Fill a bubble to check yourself
D Correct answer
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=$\frac{802}{18}=44\frac{5}{9}$

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

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
Reveal answer Fill a bubble to check yourself
C Correct answer
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

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

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

  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. $1$
Reveal answer Fill a bubble to check yourself
D Correct answer
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