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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