# NCERT Solutions for Class 8 Maths Exercise 7.2 ## myCBSEguide App

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NCERT solutions for Class 8 Maths Cubes and Cube Roots ## NCERT Solutions for Class 8 Maths Cubes and Cube Roots

###### 1. Find the cube root of each of the following numbers by prime factorization method:

(i) 64

(ii) 512

(iii) 10648

(iv) 27000

(v) 15625

(vi) 13824

(vii) 110592

(viii) 46656

(ix) 175616

(x) 91125

Ans. (i) 64  = = 4 (ii) 512 = = 8 (iii) 10648 = = 22 ###### (iv) 27000 = = 30 ###### (v) 15625 = = 25 (vi) 13824 = = 24 (vii) 110592 = = 48 (viii) 46656 = = 36 (ix) 175616 = = 56 (x) 91125 = = 45 NCERT Solutions for Class 8 Maths Exercise 7.2

###### 2. State true or false:

(i) Cube of any odd number is even.

(ii) A perfect cube does not end with two zeroes.

(iii) If square of a number ends with 5, then its cube ends with 25.

(iv) There is no perfect cube which ends with 8.

(v) The cube of a two digit number may be a three digit number.

(vi) The cube of a two digit number may have seven or more digits.

(vii) The cube of a single digit number may be a single digit number.

Ans. (i) False

Since, are all odd.

(ii) True

Since, a perfect cube ends with three zeroes. e.g. so on

(iii) False

Since, (Did not end with 25)

(iv) False

Since = 1728

[Ends with 8]

And = 10648

[Ends with 8]

(v) False Since = 1000

[Four digit number]

And = 1331

[Four digit number]

(vi) False Since = 970299

[Six digit number]

(vii) True = 1

[Single digit number] = 8

[Single digit number]

NCERT Solutions for Class 8 Maths Exercise 7.2

###### 3. You are told that 1,331 is a perfect cube. Can you guess with factorization what is its cube root? Similarly guess the cube roots of 4913, 12167, 32768.

Ans. We know that = 1000 and Possible cube of = 1331

Since, cube of unit’s digit = 1

Therefore, cube root of 1331 is 11.

4913

We know that = 343

Next number comes with 7 as unit place = 4913

Hence, cube root of 4913 is 17.

12167

We know that = 27

Here in cube, ones digit is 7

Now next number with 3 as ones digit = 2197

And next number with 3 as ones digit = 12167

Hence cube root of 12167 is 23.

32768

We know that = 8

Here in cube, ones digit is 8

Now next number with 2 as ones digit = 1728

And next number with 2 as ones digit = 10648

And next number with 2 as ones digit = 32768

Hence cube root of 32768 is 32.

## NCERT Solutions for Class 8 Maths Exercise 7.2

NCERT Solutions Class 8 Mathematics PDF (Download) Free from myCBSEguide app and myCBSEguide website. Ncert solution class 8 Mathematics includes text book solutions from Class 8 Maths Book . NCERT Solutions for CBSE Class 8 Maths have total 16 chapters. 8 Maths NCERT Solutions in PDF for free Download on our website. Ncert class 8 solutions PDF and Maths ncert class 8 PDF solutions with latest modifications and as per the latest CBSE syllabus are only available in myCBSEguide.

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