Tag: mental additions and subtractions

Questions Related to mental additions and subtractions

2530 soldiers were sent out on a mission. Each army truck could carry a maximum of 55 soldiers. How many army trucks were needed to carry all 2530 soldiers ?

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

  1. 44

  2. 45

  3. 46

  4. 47

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Correct Option: C
Explanation:

Each army truck could carry a maximum soldiers $=55$


Therefore, the number of trucks are required for $2530$ soldiers
$=\dfrac{2530}{55}$
$=46$ trucks

Hence, this is the answer.

A balloon seller sold 236 red balloons, 23 white balloons and 749 blue balloons. How many balloons were sold in all ?

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

  1. 186

  2. 654

  3. 1,005

  4. 1,008

Show answer
Correct Option: D
Explanation:

A balloon seller sold $=236$ red balloons

$=23$ white balloons
$=749$ blue balloons

Therefore, the total numbers of balloons will be sold
$=236+23+749$
$=1008$

Hence, this is the answer.

$ \displaystyle  \Uparrow \,  \Uparrow\, \Uparrow\, \Uparrow   $  Number represented by figures is ,if each symbol represents 5 houses

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

  1. 4

  2. 20

  3. 5

  4. 40

Show answer
Correct Option: B
Explanation:

There are 4 symbols used in the question to depict houses.

Each symbol = 5 houses.
So total number of houses= 4×5 = 20 houses.
Hence option B is the correct answer.

The sum of all even natural numbers between $1$ and $31$ is:

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

  1. $16$

  2. $128$

  3. $240$

  4. $512$

Show answer
Correct Option: C
Explanation:

Required sum $=(2+4+6+......+30)$
This is an A.P in which $a=2,d=(4-2)=2$ and $l=30$.
Let the number of terms be $n$. Then,
${t} _{n}=30$ $\Rightarrow$ $a+(n-1)d=30$
$\Rightarrow$ $2+(n-1)\times 2=30$
$\Rightarrow$ $n-1=14$
$\Rightarrow$ $n=15$
$\therefore$ ${S} _{n}=\cfrac{n}{2}(a+l)=\cfrac{15}{2}\times (2+30)=240$

If Seema and Reema has $10$ and $6$ chocolates respectively. Find the total number of chocolates.

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

  1. $10$

  2. $6$

  3. $16$

  4. $4$

Show answer
Correct Option: C
Explanation:

Number of chocolates with Seema $=10$

Number of chocolates with Reema $=6$
$\therefore$ total number of chocolates $=10+6=16$
Option $C$ is correct

A box contains $25$ packets of pencils. Sachin takes $7$ packets, Ajay takes $8$ packet. How many packets are left in the box?

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

  1. $25$

  2. $10$

  3. $18$

  4. $17$

Show answer
Correct Option: B
Explanation:

Total number of packets  pencils $=25$

Number of packets pencils taken by Sachin $=7$
Number of packets of pencils taken by Ajay $=8$
Number of packets left $=25-7-8=10$
Thus, the correct answer is $10$.

Ravi has $15$ magic pens. If he gives $4$ magic pens to Suraj, then the number of pens Ravi left with is :

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

  1. $19$

  2. $11$

  3. $4$

  4. $15$

Show answer
Correct Option: B
Explanation:

Number of magic pens with Ravi $=15$

Number of pens he given to Suraj $=4$
So number of pens left with Ravi $=15-4=11$
Thus, the correct answer is $11$.

Negative integers are at ___________ side of $0$ on numberline.

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

  1. Left

  2. Right

  3. Middle

  4. None of the above

Show answer
Correct Option: A
Explanation:

Negative numbers lie left side of Zero.

Positive integers are at ______________ side of $0$ on numberline.

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

  1. Left

  2. Right

  3. Middle

  4. None of the above

Show answer
Correct Option: B
Explanation:

Positive Numbers lie right side of Zero on numberline.

Richa walks $4km$ in the direction of sun on sunset time. Then she turns a right and walks $1km$. She turns left and walks $1km$ then she turns left and walks $1km$. Find displacement of her walk in km?

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

  1. $3$

  2. $4$

  3. $5$

  4. $6$

Show answer
Correct Option: C
Explanation:
So it will be simple displacement.
First she walks $4$ km and then turn right and walk $ 1$ km 
Then she turn left and walk $1$ km and finally turn left and walk $1$ km .
If you draw this in paper then you will clearly that she is $4$+$1$=$5$ km away form the origin.