Tag: calculating and mental strategies 3

Questions Related to calculating and mental strategies 3

The sum of first 100 natural numbers is divisible by

maths calculating and mental strategies 3 written methods dividing decimals division of decimals

  1. $10$

  2. $100$

  3. $50$

  4. All the above

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Correct Option: D
Explanation:

The sum of the $n$ natural numbers =$\frac{n\times (n+1)}{2}$
Here,$n=100$
$\therefore$ Sum=$\frac{100\times (100+1)}{2}$
$=\frac{100\times 101}{2}$
$=5050$
Option is D

How many numbers from 1 to 100 written in decimal form have the digit 5 in them?

maths calculating and mental strategies 3 written methods dividing decimals division of decimals

  1. $11$

  2. $10$

  3. $15$

  4. $19$

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Correct Option: D
Explanation:

The numbers can be easily counted.
5,15,25,35,45,50,51,52,53,54,55,56,57,58.59.65.75.85.95
Thus, there are 19 numbers

The number equal to 7 hundredths is

maths calculating and mental strategies 3 written methods dividing decimals division of decimals

  1. 0.7

  2. 0.07

  3. 0.007

  4. 1.07

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Correct Option: B
Explanation:

$\frac{7}{100} = 0.07$

The number equal to 22 thousandths is

maths calculating and mental strategies 3 written methods dividing decimals division of decimals

  1. 0.22

  2. 0.022

  3. 2.022

  4. 2.202

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Correct Option: B
Explanation:

$\frac{22}{1000} = 0.022$

$\displaystyle 225.500\div 0.5$ =

maths calculating and mental strategies 3 written methods dividing decimals division of decimals

  1. 4.51

  2. 45.1

  3. 451

  4. .451

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Correct Option: C
Explanation:

correct option is C..

Solve:
$\displaystyle 122.5 \div 1000 = $

maths calculating and mental strategies 3 written methods dividing decimals division of decimals

  1. $.01225$

  2. $.1225$

  3. $1.225$

  4. $12.25$

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Correct Option: B
Explanation:

$122.5/1000$

$=1225/10000$
$=0.1225$
Hence Option B

If the cost of $20$ fans is Rs. $248.50$, then the cost of one fan is

maths calculating and mental strategies 3 written methods dividing decimals division of decimals

  1. $Rs.\ 12.46$

  2. $Rs.\ 12.42$

  3. $Rs.\ 12.40$

  4. $Rs.\ 12.425$

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Correct Option: D
Explanation:

cost of $20$ fans = Rs. $248.50$

cost of $1$ fan = Rs. $248.50/20$=$12.425$ Rs.
Hence Option D

3 tenth 5 thousandths is written as

maths calculating and mental strategies 3 written methods dividing decimals division of decimals

  1. 35.00

  2. 0.35

  3. 3.5

  4. 0.305

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Correct Option: D
Explanation:

The first decimal digit from the decimal point is the tenth, the second decimal digit from the decimal point is the hundredth and the third decimal digit from the decimal point is the thousandths digit. 


Read the whole set of three decimal digits as a number, and say, "tenths", "hundredths" and “thousandths.” 0.305 has 3 tenths, 0 hundredths, and 5 thousandths. While 0.305 is the sum of 3/10, 0/100, and 5/1000, it is also 305/1000.

So option D is the correct answer.

Divide $150.75\div 0.6$

maths calculating and mental strategies 3 written methods dividing decimals division of decimals

  1. 251.25

  2. 2512.5

  3. 25125

  4. 25.125

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Correct Option: A
Explanation:

$150.75\div 0.6$

$\Rightarrow$  $\dfrac{150.75}{0.6}=\dfrac{150.75\times 10}{0.6\times 10}$

                     $=\dfrac{1507.5}{6}$

                     $=251.25$

$143.6\div 2000= .............$

maths calculating and mental strategies 3 written methods dividing decimals division of decimals

  1. 0.1718

  2. 7.18

  3. 0.718

  4. 0.0718

Show answer
Correct Option: D
Explanation:

$143.6\div 2000=71.8\div 1000$
$=0.0718$