Tag: maths

Questions Related to maths

Round-off $76,890$ to nearest $10$.

maths mental arithmetic estimation and rounding off estimations, bounds and rounding off rounding off numbers rounding of decimals

  1. $76,890$

  2. $76,880$

  3. $76,900$

  4. $77,000$

Show answer
Correct Option: A
Explanation:

$\Rightarrow$   The given number is $76,890$.

$\Rightarrow$   In number 76890, its unit digit is $0$, which is already nearest to 10.
$\Rightarrow$  So, don't need to change anything.
$\therefore$   $76,890$ is nearest to 10.

Round-off $4353$ to nearest $100$.

maths mental arithmetic estimation and rounding off estimations, bounds and rounding off rounding off numbers rounding of decimals

  1. $4353$

  2. $4350$

  3. $4360$

  4. $4400$

Show answer
Correct Option: D
Explanation:

$\Rightarrow$  The given number is $4353$

$\Rightarrow$  In number 4353, its tens digit is 5, which is equal to 5. 
$\Rightarrow$  So, we increase the digits at hundreds place by 1 and replace each one of the digits at tens and ones place by 0 to round off the given number to nearest to 100.

$\therefore$   The number becomes $4400$

Round-off $52,398$ to nearest $1000$.

maths mental arithmetic estimation and rounding off estimations, bounds and rounding off rounding off numbers rounding of decimals

  1. $52,390$

  2. $52,400$

  3. $52,000$

  4. $53,000$

Show answer
Correct Option: C
Explanation:

$\Rightarrow$  The given number is $52,398$

$\Rightarrow$  In number $52398$, its hundred digit is $3$, which is less than $5$. 
$\Rightarrow$  So, we replace each one of the digits at hundreds, tens and ones place by $0$ to round off the given number to nearest to $1000$.

$\therefore$   The number becomes $52,000$

Round-off $3789$ to nearest $100$

maths mental arithmetic estimation and rounding off estimations, bounds and rounding off rounding off numbers rounding of decimals

  1. $3789$

  2. $3790$

  3. $3800$

  4. $4000$

Show answer
Correct Option: C
Explanation:

$\Rightarrow$  The given number is $3789$

$\Rightarrow$  In number 3789, its tens digit is 8, which is greater than 5. 
$\Rightarrow$  So, we increase the digits at hundreds place by 1 and replace each one of the digits at tens and ones place by 0 to round off the given number to nearest to 100.

$\therefore$   The number becomes $3800$

Round-off $47,897$ to nearest $1000$.

maths mental arithmetic estimation and rounding off estimations, bounds and rounding off rounding off numbers rounding of decimals

  1. $47,897$

  2. $48,000$

  3. $47,900$

  4. $47,890$

Show answer
Correct Option: B
Explanation:

$\Rightarrow$  The given number is $47,897$

$\Rightarrow$  In number 47897, its hundred digit is 8, which is greater than 5. 
$\Rightarrow$  So, we increase the digits at thousand place by 1 and replace each one of the digits at hundreds, tens and ones place by $0$ to round off the given number to nearest to 1000.

$\therefore$   The number becomes $48,000$

Fill in the blanks.
(i) The number 825642 rounded off to nearest thousand is   P  .
(ii) Estimated product of 4023 and 198 is   Q  .
(iii) CXXXI is written in Hindu-Arabic numeral as    R   .
P   Q   R

maths mental arithmetic estimation and rounding off estimations, bounds and rounding off rounding off numbers rounding of decimals

  1. 820000 800000 131

  2. 826000 800000 131

  3. 826000 850000 135

  4. 825000 800000 135

Show answer
Correct Option: B
Explanation:

(i) 825642 rounded off to nearest thousand = 826000
(ii) 4023 estimated to 4000
 198 estimated to 200.
$\therefore$ estimated product = $4000\times 200$ = 800000
(iii) C denoted for 100
     X denotes for 10  
      I denotes for 1
$\therefore$ CXXXI denotes 131

State 'T' for true and 'F' for false.
I. Rounding off $2560$ to the nearest thousand, we get $2000$.
II. Place value of $9$ in $974304200 $ is ninety crore.
Ill. $1$ lakh $= 1000$ thousand
IV. Roman numeral for the smallest four-digit number is $M$.
I  II  III  IV

maths mental arithmetic estimation and rounding off estimations, bounds and rounding off rounding off numbers rounding of decimals

  1. T F T F

  2. F F T T

  3. T T T T

  4. F T F T

Show answer
Correct Option: D
Explanation:

I.Rounding off $2560$ to the nearest thousand, we get $3000$. 

So, I is false
II. Place value of $9$ in $90,00,00,000$. 

So, II is true
III. $1$ lakh $= 1,00,000 = 100 $ thousand
IV. Smallest four digit number $= 1000$
Roman Numeral is $M$.
So, it is true

Estimate the difference of $15875 $ and $7892$ by rounding off each number to nearest hundred.

maths mental arithmetic estimation and rounding off estimations, bounds and rounding off rounding off numbers rounding of decimals

  1. $7983$

  2. $8100$

  3. $7900$

  4. $8000$

Show answer
Correct Option: D
Explanation:

$15875$ estimated to nearest hundred is $15900$
$7892 $ estimated to nearest hundred is $7900$
Thherefore, required difference is $15900-7900 =8000$.

What will be the rounded off sum of these figures, $2.303 + 6.66 $ to two decimal point?

maths mental arithmetic estimation and rounding off estimations, bounds and rounding off rounding off numbers rounding of decimals

  1. $8.969$

  2. $8.96$

  3. $8.9$

  4. $8.97$

Show answer
Correct Option: B
Explanation:

$2.303+6.66=8.963$


It can rounded off and written as $8.96$ $.$

Mark the correct alternative of the following.
Total number of numbers which when rounded off to nearest ten give us $200$ is?

maths mental arithmetic estimation and rounding off estimations, bounds and rounding off rounding off numbers rounding of decimals

  1. $9$

  2. $10$

  3. $8$

  4. $7$

Show answer
Correct Option: B
Explanation:

$195, 196, 197, 198, 199, 200, 201, 202, 203, 204$ are the numbers that when rounded off to nearest ten give us $200$.


Hence, total number of numbers which when rounded off to nearest ten give us $200$ is $10$.