Tag: mental additions and subtractions

Questions Related to mental additions and subtractions

What number should be subtracted from each of the numbers 54, 71, 75 and 99, so that the remainders may be in proportion?

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 5

  2. 4

  3. 3

  4. 2

Show answer
Correct Option: C
Explanation:

Let the number to be subtracted is $x$

$(54-x),  (71-x),   (75-x)$  and $ (99-x)$ are in proportion

$\Rightarrow \dfrac{54-x}{71-x}=\dfrac{75-x}{94-x}$ Which is true if $x=3$


$\Rightarrow \dfrac{54-3}{71-3}=\dfrac{75-3}{94-3}$

$\Rightarrow \dfrac{51}{68}=\dfrac{72}{91}$

i.e $\Rightarrow \dfrac{3}{4}=\dfrac{3}{4}$

Then subtracted $3$ in these number may be in proportion  

Sum of the greatest 8 digit number and the smallest 9 digit number is

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 1,99,99,999

  2. 19,99,99,999

  3. 99,99,99,999

  4. 1,00,00,999

Show answer
Correct Option: B
Explanation:

Greatest - 8 digit no. 99999999
Smallest - 9 digit no. $\underline {100000000}$
                                  $=\underline {199999999}$

A student was asked to multiply a certain number by 3 and to add 2 to it, but he divided the number by 3 and subtracted 2 from it and got the number 1. The correct answer is

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 9

  2. 25

  3. 29

  4. none of these

Show answer
Correct Option: C
Explanation:

Let the certain number be x
As per problem,
$\Rightarrow \frac { x }{ 3 } -2=1$
 $\Rightarrow \frac { x-6 }{ 3 } =1$
 $\Rightarrow x-6=3$
 $\Rightarrow x=9$
The correct answer will be $9\times 3+2=27+2=29$

A shopkeeper had a stock of 23,898 kg of wheat out of which 1,795 kg is sold in the morning and 2,348 kg of wheat is sold in the evening. Quantity of wheat left in the shop is

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 1,97,555 kg

  2. 197 kg

  3. 19,755 kg

  4. 1,975 kg

Show answer
Correct Option: C
Explanation:

Stock $=23,898 kg$.
Stock sold in morning $=1,795$
Stock sold in evening $=\underline {2,348}$
                                         $\underline {4,143}$
  Stock left $=23,898-4143$
$=19,755 kg$.

The population of a city is 5,12,10,913. Out of which 23,05,218 were males, 18,47,525 were females and remaining are children. The number of children in the city is

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 4,70,58,170

  2. 5,53,63,656

  3. 5,07,53,220

  4. 5,16,68,606

Show answer
Correct Option: A
Explanation:

   $18,47,525$
$+\underline {23,05,218}$
  $\underline { 41,52,743}$
$\therefore$ Number of children
$=5,12,10,913-41,52,743$
$=4,70,58,170$

Is it possible to make 1000 with eight 8's in any way by using any operation?

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. Yes

  2. No

  3. Impossible

  4. None of these

Show answer
Correct Option: A
Explanation:

888
088
008
008
$\underline {+8}$
$\underline {1000}$

The maximum temperature on a day is 35$^o$C and the minimum temperature is 25$^o$C. The difference of these temperatures, on Fahrenheit scale is

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 25$^o$F

  2. 75$^o$F

  3. 50$^o$F

  4. 100$^o$F

Show answer
Correct Option: C
Explanation:

$35^oC- 25^o C = 10^oC$
$10^o C = \displaystyle \left( 10 \times \frac{9}{5} \right ) + 32$
$= 18 + 32 = 50^o F$.

Sum of $2.8, 26.3$ and $62.874$ is ______

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. $91.974$

  2. $9.1974$

  3. $919.74$

  4. $9197.4$

Show answer
Correct Option: A
Explanation:

To add Various numbers with different decimal points we pick the number with the largest decimal point and extend the others to the same decimal point.


In our question,

$2.800+26.300+62.874= 91.974$

So option A is the correct answer.

A shopkeeper sold$\  12.750\  kg$ of sugar on a day. On the next day he sold$\ 38.250\ kg$ of sugar. On the third day he sold $\ 50.50\  kg$ of sugar. How much of sugar in all did the shopkeeper sell?

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 100 kg

  2. 101.5 kg

  3. 102.5 kg

  4. 101 kg

Show answer
Correct Option: B
Explanation:

The amount of sugar sold on first day = 12.75 Kg

The amount of sugar sold on second day = 38.25 Kg
The amount of sugar sold on third day = 50.50 Kg

We have to calculate the total sugar sold by the shopkeeper. Thus, we have to take the sum of sugar sold on all three days.

$\therefore$ The total sugar sold by the shopkeeper is $12.75 + 38.25 + 50.50 = 101.5$

In a movie hall, 363 seats are vacant and 1560 seats are occupied. What is the seating capacity of the hall ?

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 1923

  2. 2000

  3. 1900

  4. 2393

Show answer
Correct Option: A
Explanation:

In a movie hall, the vacant seats are $=363$

And occupied seats are $=1560$

Therefore, the capacity of the hall will be
$=1560+363$
$=1923$

Hence, this is the answer.