Cube of 0.21
2026-02-28 19:09 Diff
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Last updated on August 5, 2025

When a number is multiplied by itself thrice, the resultant number is called the cube of a number. Cubing is used in comparing sizes of objects or things with cubic measurements. In this topic, we shall learn about cubes of 0.21.

Cube of 0.21

A cube number is a value obtained by raising a number to the power of 3, or by multiplying the number by itself three times.

When you cube a positive number, the result is always positive.

When you cube a negative number, the result is always negative.

This is because a negative number by itself three times results in a negative number.

The cube of 0.21 can be written as 0.21³, which is the exponential form.

Or it can also be written in arithmetic form as, 0.21 × 0.21 × 0.21.

How to Calculate the Value of Cube of 0.21

In order to check whether a number is a cube number or not, we can use the following three methods, such as multiplication method, a factor formula (a³), or by using a calculator. These three methods will help kids to cube the numbers faster and easier without feeling confused or stuck while evaluating the answers.

  • By Multiplication Method
     
  • Using a Formula (a3)
     
  • Using a Calculator

By Multiplication Method

The multiplication method is a process in mathematics used to find the product of two numbers or quantities by combining them through repeated addition. It is a fundamental operation that forms the basis for more complex mathematical concepts.

Step 1: Write down the cube of the given number. 0.21³ = 0.21 × 0.21 × 0.21

Step 2: You get approximately 0.009261 as the answer.

Hence, the cube of 0.21 is approximately 0.009261.

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Using a Formula (a³)

The formula (a + b)³ is a binomial formula for finding the cube of a number. The formula is expanded as a³ + 3a²b + 3ab² + b³.

Step 1: Split the number 0.21 into two parts, as 0.2 and 0.01. Let a = 0.2 and b = 0.01, so a + b = 0.21

Step 2: Now, apply the formula (a + b)³ = a³ + 3a²b + 3ab² + b³

Step 3: Calculate each term a³ = 0.2³ 3a²b = 3 × 0.2² × 0.01 3ab² = 3 × 0.2 × 0.01² b³ = 0.01³

Step 4: Add all the terms together: (a + b)³ = a³ + 3a²b + 3ab² + b³ (0.2 + 0.01)³ = 0.2³ + 3 × 0.2² × 0.01 + 3 × 0.2 × 0.01² + 0.01³ 0.21³ = 0.008 + 0.0012 + 0.000006 + 0.000001 0.21³ = 0.009207

Step 5: Hence, the cube of 0.21 is approximately 0.009207.

Using a Calculator

To find the cube of 0.21 using a calculator, input the number 0.21 and use the cube function (if available) or multiply 0.21 × 0.21 × 0.21. This operation calculates the value of 0.21³, resulting in approximately 0.009261. It’s a quick way to determine the cube without manual computation.

Step 1: Ensure the calculator is functioning properly.

Step 2: Press 0.2 followed by 1

Step 3: If the calculator has a cube function, press it to calculate 0.21³.

Step 4: If there is no cube function on the calculator, simply multiply 0.21 three times manually.

Step 5: The calculator will display approximately 0.009261.

Tips and Tricks for the Cube of 0.21

  • The cube of any positive number is always positive, while the cube of any negative number is always negative.
     
  • The product of two or more perfect cube numbers is always a perfect cube.
     
  • A perfect cube can always be expressed as the product of three identical groups of equal prime factors.

Common Mistakes to Avoid When Calculating the Cube of 0.21

There are some typical errors that kids might make during the process of cubing a number. Let us take a look at five of the major mistakes that kids might make:

Problem 1

What is the cube and cube root of 0.21?

Okay, lets begin

The cube of 0.21 is approximately 0.009261, and the cube root of 0.21 is approximately 0.596.

Explanation

First, let’s find the cube of 0.21.

We know that cube of a number, such that x³ = y

Where x is the given number, and y is the cubed value of that number

So, we get 0.21³ = 0.009261 Next, we must find the cube root of 0.21

We know that cube root of a number ‘x’, such that ∛x = y

Where ‘x’ is the given number, and y is the cube root value of the number So, we get ∛0.21 ≈ 0.596

Hence the cube of 0.21 is approximately 0.009261, and the cube root of 0.21 is approximately 0.596.

Well explained 👍

Problem 2

If the side length of a cube is 0.21 m, what is the volume?

Okay, lets begin

The volume is approximately 0.009261 m³.

Explanation

Use the volume formula for a cube V = Side³.

Substitute 0.21 for the side length: V = 0.21³ ≈ 0.009261 m³.

Well explained 👍

Problem 3

How much larger is 0.21³ than 0.2³?

Okay, lets begin

0.21³ – 0.2³ ≈ 0.001261.

Explanation

First find the cube of 0.21³, that is approximately 0.009261

Next, find the cube of 0.2³, which is 0.008

Now, find the difference between them using the subtraction method. 0.009261 – 0.008 = 0.001261

Therefore, the 0.21³ is approximately 0.001261 larger than 0.2³.

Well explained 👍

Problem 4

If a cube with a side length of 0.21 m is compared to a cube with a side length of 0.1 m, how much larger is the volume of the larger cube?

Okay, lets begin

The volume of the cube with a side length of 0.21 m is approximately 0.009261 m³.

Explanation

To find its volume, we multiply the side length by itself three times (since it’s a 3-dimensional object).

Cubing 0.21 means multiplying 0.21 by itself three times: 0.21 × 0.21 = 0.0441, and 0.0441 × 0.21 ≈ 0.009261.

The unit of volume is cubic meters (m³), because we are calculating the space inside the cube.

Therefore, the volume of the cube is approximately 0.009261 m³.

Well explained 👍

Problem 5

Estimate the cube 0.199 using the cube 0.2.

Okay, lets begin

The cube of 0.199 is approximately 0.008.

Explanation

First, identify the cube of 0.2,

The cube of 0.2 is 0.2³ = 0.008.

Since 0.199 is only a tiny bit less than 0.2, the cube of 0.199 will be almost the same as the cube of 0.2.

The cube of 0.199 is approximately 0.008 because the difference between 0.199 and 0.2 is very small.

So, we can approximate the value as 0.008.

Well explained 👍

FAQs on Cube of 0.21

1.What are the perfect cubes up to 0.21?

The perfect cubes up to 0.21 are 0.001, 0.008, and 0.027.

2.How do you calculate 0.21³?

To calculate 0.21³, use the multiplication method, 0.21 × 0.21 × 0.21, which equals approximately 0.009261.

3.What is the meaning of 0.21³?

0.21³ means 0.21 multiplied by itself three times, or 0.21 × 0.21 × 0.21.

4.What is the cube root of 0.21?

The cube root of 0.21 is approximately 0.596.

5.Is 0.21 a perfect cube?

No, 0.21 is not a perfect cube because no integer multiplied by itself three times equals 0.21.

Important Glossaries for Cube of 0.21

  • Binomial Formula: It is an algebraic expression used to expand the powers of a number, written as (a + b)ⁿ, where ‘n’ is a positive integer raised to the base. The formula is used to find the square and cube of a number.
  • Cube of a Number: Multiplying a number by itself three times is called the cube of a number.
  • Exponential Form: It is a way of expressing numbers using a base and an exponent (or power), where the exponent value indicates how many times the base is multiplied by itself. For example, 2³ represents 2 × 2 × 2, which equals 8.
  • Perfect Cube: A number that can be expressed as the product of an integer with itself twice is a perfect cube.
  • Volume of a Cube: The amount of space occupied by a cube, calculated as the cube of the side length. For example, if the side length is 0.21, the volume is 0.21³.

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Jaskaran Singh Saluja

About the Author

Jaskaran Singh Saluja is a math wizard with nearly three years of experience as a math teacher. His expertise is in algebra, so he can make algebra classes interesting by turning tricky equations into simple puzzles.

Fun Fact

: He loves to play the quiz with kids through algebra to make kids love it.