Cube of 81

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 81 can be written as 81³, which is the exponential form.

Or it can also be written in arithmetic form as 81 × 81 × 81.

In order to check whether a number is a cube number or not, we can use the following three methods: 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

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. 81³ = 81 × 81 × 81

Step 2: You get 531,441 as the answer.

Hence, the cube of 81 is 531,441.

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 81 into two parts. Let a = 80 and b = 1, so a + b = 81

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

Step 3: Calculate each term a³ = 80³ 3a²b = 3 × 80² × 1 3ab² = 3 × 80 × 1² b³ = 1³

Step 4: Add all the terms together: (a + b)³ = a³ + 3a²b + 3ab² + b³ (80 + 1)³ = 80³ + 3 × 80² × 1 + 3 × 80 × 1² + 1³ 81³ = 512,000 + 19,200 + 240 + 1 81³ = 531,441

Step 5: Hence, the cube of 81 is 531,441.

To find the cube of 81 using a calculator, input the number 81 and use the cube function (if available) or multiply 81 × 81 × 81. This operation calculates the value of 81³, resulting in 531,441. It’s a quick way to determine the cube without manual computation.

Step 1: Ensure the calculator is functioning properly.

Step 2: Press 8 followed by 1

Step 3: If the calculator has a cube function, press it to calculate 81³.

Step 4: If there is no cube function on the calculator, simply multiply 81 three times manually.

Step 5: The calculator will display 531,441.

The cube of any even number is always even, while the cube of any odd number is always odd. 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.

• 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 equals 8.

• Perfect Cube: A number that can be expressed as the cube of an integer. For example, 27 is a perfect cube because it is 3³.

• Cube Root: A number that, when multiplied by itself three times, gives the original number. For example, the cube root of 27 is 3.