Let’s do this by examples

 

Is 216 a perfect cube?

Let’s do prime factorization of 216

checking if perfect cube.jpg

Thus,

 216  = 2 × 2 × 2 × 3 × 3 × 3

 

Now,

We make groups of 3

Checking if perfect cube - Part 2

Since 2 & 3 occur in triplets.

∴ 216 is a perfect cube.

 

Cube root of 216 = 2 × 3

         = 6

 

Is 729 a perfect cube?

Doing Prime factorization of 729

Checking if perfect cube - Part 3

We see that

Checking if perfect cube - Part 4

 

Since 3 occurs in triplets.

∴ 729 is a perfect cube.

 

Cube root of 729 = 3 × 3

 

Is 3375 a perfect cube?

Doing Prime factorization of 3375

Checking if perfect cube - Part 5

We see that

Checking if perfect cube - Part 6

Since 3 & 5 occurs in triplets.

∴ 3375 is a perfect cube.

 

Cube root of 3375 = 3 × 5

       = 15

 

Is 1125 a perfect cube?

Doing Prime factorization of 1125

Checking if perfect cube - Part 7

We see that

Checking if perfect cube - Part 8

Since 3 does not occur in triplets

∴ 1125 is not a perfect cube.

 

Is 6859 a perfect cube?

Doing Prime factorization of 6859

Checking if perfect cube - Part 9

We see that

Checking if perfect cube - Part 10

Since 19 occurs in triplets.

∴ 6859 is a perfect cube.

 

Cube root of 6859 = 19

 

Is 10648 a perfect cube?

Doing Prime factorization of 10648

Checking if perfect cube - Part 11

We see that Checking if perfect cube - Part 12

Since 2 & 11 occurs in triplets.

∴ 10648 is a perfect cube.

 

Cube root of 10648 = 2 × 11

        = 22

 

Is 5324 a perfect cube?

Doing Prime factorization of 5324

Checking if perfect cube - Part 13

We see that

Checking if perfect cube - Part 14

Since 2 does not occur in triplets.

∴ 5324 is not a perfect cube.

 

Is 968 a perfect cube?

Doing Prime factorization of 968

Checking if perfect cube - Part 15

We see that

Checking if perfect cube - Part 16

Since 11 does not occur in triplets.

∴ 968 is not a perfect cube

 

Is 400 a perfect cube?

Doing Prime factorization of 400

Checking if perfect cube - Part 17

Since 2 & 5 do not occur in triplets.

∴ 400 is not a perfect cube.

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo