NCERT Exercise 2.7 solution

Fractions and Decimals 7th Math

NCERT Exercise 2.7 solution

Division of a decimal number by a whole number

Question (1) Find:

(i) 0.4 ÷ 2

Solution :

Given, 0.4 ÷ 2

`=0.4xx1/2`

= 0.2 Answer

Alternate Method to Divide a Decimal Number

Given, 0.4 ÷ 2

`=(cancel4 2)/10xx1/cancel2`

`=2/10`

= 0.2 Answer

(ii) 0.35 ÷ 5

Solution :

Given, 0.35 ÷ 5

`=0.35xx1/5`

= 0.07 Answer

Alternate Method to Divide a Decimal Number

Given, 0.35 ÷ 5

`=(cancel35 7)/100xx1/cancel5`

`=7/100`

= 0.07 Answer

(iii) 2.48 ÷ 4

Solution :

Given, 2.48 ÷ 4

`=2.48xx1/4`

= 0.62 Answer

Alternate Method to Divide a Decimal Number

Given, 2.48 ÷ 4

`=(cancel248 62)/100xx1/cancel4`

`=62/100`

= 0.62 Answer

(iv) 65.4 ÷ 6

Solution :

Given, 65.4 ÷ 6

`=65.4xx1/6`

= 10.9 Answer

Alternate Method to Divide a Decimal Number

Given, 65.4 ÷ 6

`=(cancel654 109)/10xx1/cancel6`

`=109/10`

= 10.9 Answer

(v) 651.2 ÷ 4

Solution :

Given, 651.2 ÷ 4

`=651.2xx1/4`

= 162.8 Answer

Alternate Method to Divide a Decimal Number

Given, 651.2 × 4

`=(cancel6512 1628)/10xx1/cancel4`

`=1628/10`

= 162.8 Answer

(vi) 14.49 ÷ 7

Solution :

Given, 14.49 ÷ 7

`=14.49xx1/7`

= 2.07 Answer

Alternate Method to Divide a Decimal Number

Given, 14.49 ÷ 7

`=(cancel1449 207)/100xx1/cancel7`

`=207/100`

= 2.07 Answer

(vii) 3.96 ÷ 4

Solution :

Given, 3.96 ÷ 4

`=3.96xx1/4`

= 0.99 Answer

Alternate Method to Divide a Decimal Number

Given, 3.96 ÷ 4

`=(cancel396 99)/100xx1/cancel4`

`=99/100`

= 0.99 Answer

(viii) 0.80 ÷ 5

Solution :

Given, 0.80 ÷ 5

`=0.80xx1/5`

= 0.16 Answer

Alternate Method to Divide a Decimal Number

Given, 0.80 ÷ 5

`=(cancel80 16)/100xx1/cancel5`

`=16/100`

= 0.16 Answer

Division of a decimal number by 10

Question (2) Find

(i) 4.8 ÷ 10

Solution :

Given, 4.8 ÷ 10

`=4.8xx1/10`

= 0.48 Answer

Alternate Method to Divide a Decimal Number

Given, 4.8 ÷ 10

`=48/10xx1/10`

`=48/100`

= 0.48 Answer

(ii) 52.5 ÷ 10

Solution :

Given, 52.5 ÷ 10

`=52.5xx1/10`

= 5.25 Answer

Alternate Method to Divide a Decimal Number

Given, 52.5 ÷ 10

`=525/10xx1/10`

`=525/100`

= 5.25 Answer

(iii) 0.7 ÷ 10

Solution :

Given, 0.7 ÷ 10

`=0.7xx1/10`

= 0.07 Answer

Alternate Method to Divide a Decimal Number

Given, 0.7 ÷ 10

`=7/10xx1/10`

`=7/100`

= 0.07 Answer

(iv) 33.1 ÷ 10

Solution :

Given, 33.1 ÷ 10

`=33.1xx1/10`

= 3.31 Answer

Alternate Method to Divide a Decimal Number

Given, 33.1 ÷ 10

`=331/10xx1/10`

`=331/100`

= 3.31 Answer

(v) 272.23 ÷ 10

Solution :

Given, 272.23 ÷ 10

`=272.23xx1/10`

= 27.223 Answer

Alternate Method to Divide a Decimal Number

Given, 272.23 ÷ 10

`=27223/100xx1/10`

`=27223/1000`

= 27.223 Answer

(vi) 0.56 ÷ 10

Solution :

Given, 0.56 ÷ 10

`=0.56xx1/10`

= 0.056 Answer

Alternate Method to Divide a Decimal Number

Given, 0.56 ÷ 10

`=56/100xx1/10`

`=56/1000`

= 0.056 Answer

(vii) 3.97 ÷ 10

Solution :

Given, 3.97 ÷ 10

`=3.97 xx 1/10`

= 0.397 Answer

Alternate Method to Divide a Decimal Number

Given, 3.97 ÷ 10

`=397/100xx1/10`

`=397/1000`

= 0.397 Answer

Division of a decimal number by 100

Question (3) Find

(i) 2.7 ÷ 100

Solution :

Given, 2.7 ÷ 100

`=2.7xx1/100`

= 0.027 Answer

Alternate Method to Divide a Decimal Number

Given, 2.7 ÷ 100

`=27/10xx1/100`

`=27/1000`

= 0.027 Answer

(ii) 0.3 ÷ 100

Solution :

Given, 0.3 ÷ 100

`=0.3xx1/100`

= 0.003 Answer

Alternate Method to Divide a Decimal Number

Given, 0.3 ÷ 100

`=3/10xx1/100`

`=3/1000`

= 0.003 Answer

(iii) 0.78 ÷ 100

Solution :

Given, 0.78 ÷ 100

`=0.78xx1/100`

= 0.0078 Answer

Alternate Method to Divide a Decimal Number

Given, 0.78 ÷ 100

`=78/100xx1/100`

`=78/10000`

= 0.0078 Answer

(iv) 432.6 ÷ 100

Solution :

Given, 432.6 ÷ 100

`=432.6xx1/100`

= 4.326 Answer

Alternate Method to Divide a Decimal Number

Given, 432.6 ÷ 100

`=4326/10xx1/100`

`=4326/1000`

= 4.326 Answer

(v) 23.6 ÷ 100

Solution :

Given, 23.6 ÷ 100

`=23.6xx1/100`

= 0.236 Answer

Alternate Method to Divide a Decimal Number

Given, 23.6 ÷ 100

`=236/10xx1/100`

`=236/1000`

= 0.236 Answer

(vi) 98.53 ÷ 100

Solution :

Given, 98.53 ÷ 100

`=98.53xx1/100`

= 0.9853 Answer

Alternate Method to Divide a Decimal Number

Given, 98.53 ÷ 100

`=9853/100xx1/100`

`=9853/10000`

= 0.9853 Answer

Division of a decimal number by 1000

Question (4) Find

(i) 7.9 ÷ 1000

Solution :

Given, 7.9 ÷ 1000

`=7.9xx1/1000`

= 0.0079 Answer

Alternate Method to Divide a Decimal Number

Given, 7.9 ÷ 1000

`=79/10xx1/1000`

`=79/10000`

= 0.0079 Answer

(ii) 26.3 ÷ 1000

Solution :

Given, 26.3 ÷ 1000

`=26.3xx1/1000`

= 0.0263 Answer

Alternate Method to Divide a Decimal Number

Given, 26.3 ÷ 1000

`=263/10xx1/1000`

`=263/10000`

= 0.0263 Answer

(iii) 38.53 ÷ 1000

Solution :

Given, 38.53 ÷ 1000

`=38.53xx1/1000`

= 0.03853 Answer

Alternate Method to Divide a Decimal Number

Given, 38.53 ÷ 1000

`=3853/100xx1/1000`

`=3853/100000`

= 0.03583 Answer

(iv) 128.9 ÷ 1000

Solution :

Given, 128.9 ÷ 1000

`=128.9xx1/1000`

= 0.1289 Answer

Alternate Method to Divide a Decimal Number

Given, 128.9 ÷ 1000

`=1289/10xx1/1000`

`=1289/10000`

= 0.1289 Answer

(v) 0.5 ÷ 1000

Solution :

Given, 0.5 ÷ 1000

`=0.5xx1/1000`

= 0.0005 Answer

Alternate Method to Divide a Decimal Number

Given, 0.5 ÷ 1000

`=5/10xx1/1000`

`=5/10000`

= 0.0005 Answer

Division of a whole number by a decimal number

Question (5) Find

(i) 7 ÷ 3.5

Solution :

Given, 7 ÷ 3.5

`=7-:35/10`

`=cancel7xx10/cancel35 5`

`=(cancel10 2)/cancel5`

= 2 Answer

(ii) 36 ÷ 0.2

Solution :

Given, 36 ÷ 0.2

`=36-:2/10`

`=cancel36 18xx10/cancel2`

= 18 × 10

= 180 Answer

Division of a decimal number by another decimal number

(iii) 3.25 ÷ 0.5

Solution :

Given, 3.25 ÷ 0.5

`=325/100-:5/10`

`=325/(cancel100 10)xxcancel10/5`

`=(cancel325 65)/10xx1/cancel5`

`=65/10`

= 6.5 Answer

Alternate Method to divide a decimal number by other decimal number

Given, 3.25 ÷ 0.5

`=3.25/0.5`

To make digits after decimal points equal, a zero is put at the right side of denominator.

`=3.25/0.50`

Now, since digits right after decimal in numerator and denominator are equal, thus, decimal will be cancelled.

`=325/50`

= 6.5 Answer

(iv) 30.94 ÷ 0.7

Solution :

Given, 30.94 ÷ 0.7

`=3094/100-:7/10`

`=3094/(cancel100 10)xxcancel10/7`

`=(cancel3094 442)/10xx1/cancel7`

`=442/10`

= 44.2 Answer

Alternate Method to divide a decimal number by other decimal number

Given, 30.94 ÷ 0.7

`=30.94/0.7`

To make digits after decimal points equal, a zero is put at the right side of denominator.

`=30.94/0.70`

Now, since digits right after decimal in numerator and denominator are equal, thus, decimal will be cancelled.

`=3094/70`

= 44.2 Answer

(v) 0.5 ÷ 0.25

Solution :

Given, 0.5 ÷ 0.25

`=5/10-:25/100`

`=cancel5/cancel10xx(cancel100 cancel10 2)/(cancel25 cancel5)`

= 2 Answer

Alternate Method to divide a decimal number by other decimal number

Given, 0.5 ÷ 0.25

`=0.5/0.25`

To make digits after decimal points equal, a zero is put at the right side of numerator.

`=0.50/0.25`

Now, since digits right after decimal in numerator and denominator are equal, thus, decimal will be cancelled.

`=50/25`

= 2 Answer

(vi) 7.75 ÷ 0.25

Solution :

Given, 7.75 ÷ 0.25

`=775/100-:25/100`

`=775/cancel100xxcancel100/25`

`=(cancel775 32)/cancel25`

= 31 Answer

Alternate Method to divide a decimal number by other decimal number

Given, 7.75 ÷ 0.25

`=7.75/0.25`

Now, since digits right after decimal in numerator and denominator are equal, thus, decimal will be cancelled.

`=775/25`

= 31 Answer

(vii) 76.5 ÷ 0.15

Solution :

Given, 76.5 ÷ 0.15

`=765/10-:15/100`

`=(cancel765 51)/cancel10xx(cancel100 10)/cancel15`

= 51 × 10

= 510 Answer

Alternate Method to divide a decimal number by other decimal number

Given, 76.5 ÷ 0.15

`=76.5/0.15`

To make digits after decimal points equal, a zero is put at the right side of numerator.

`=76.50/0.15`

Now, since digits right after decimal in numerator and denominator are equal, thus, decimal will be cancelled.

`=7650/15`

= 510 Answer

(viii) 37.8 ÷ 1.4

Solution :

Given, 37.8 ÷ 1.4

`=378/10-:14/10`

`=(cancel378 27)/cancel10xxcancel10/cancel14`

= 27 Answer

Alternate Method to divide a decimal number by other decimal number

Given, 37.8 ÷ 1.4

`=37.8/1.4`

Now, since digits right after decimal in numerator and denominator are equal, thus, decimal will be cancelled.

`=378/14`

= 27 Answer

(ix) 2.73 ÷ 1.3

Solution :

Given, 2.73 ÷ 1.3

`=273/100-:13/10`

`=(cancel273 21)/(cancel100 10)xxcancel10/cancel13`

`=21/10`

= 2.1 Answer

Alternate Method to divide a decimal number by other decimal number

Given, 2.73 ÷ 1.3

`=2.73/1.3`

To make digits after decimal points equal, a zero is put at the right side of denominator.

`=2.73/1.30`

Now, since digits right after decimal in numerator and denominator are equal, thus, decimal will be cancelled.

`=273/130`

= 2.1 Answer

Question (6) A vehicle covers a distance of 43.2 km in 2.4 litres of petrol. How much distance will it cover in one litre of petrol?

Solution :

Volume of petrol = 2.4 litre

Distance covered = 43.2 km

Thus, distance covered in 1 litre of petrol = ?

∵ In 2.4 litre of petrol, distance covered = 43.2 km

∴ In 1 litre of petrol, distance covered `=43.2/2.4` km

`=(432/10)/(24/10)` km

`=(cancel432 18)/cancel10xxcancel10/cancel24` km

= 18 km Answer

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