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Last updated on May 26th, 2025

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Cube of 7.8

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When a number is multiplied by itself thrice, the resultant number is called the cube of a number. Cubing is used when comparing sizes of objects or things with cubic measurements. In this topic, we shall learn about the cube of 7.8.

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Cube of 7.8

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 because a negative number multiplied by itself three times results in a negative number. The cube of 7.8 can be written as \(7.8^3\), which is the exponential form. Or it can also be written in arithmetic form as \(7.8 \times 7.8 \times 7.8\).

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How to Calculate the Value of the Cube of 7.8

To determine whether a number is a cube number or not, we can use the following three methods: multiplication method, a factor formula (\(a^3\)), or by using a calculator. These methods help in cubing numbers faster and easier, avoiding confusion or getting stuck during calculations. By Multiplication Method Using a Formula Using a Calculator

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By Multiplication Method

The multiplication method is a process in mathematics used to find the product of numbers by multiplying them together. It is a fundamental operation that forms the basis for more complex mathematical concepts. Step 1: Write down the cube of the given number. \(7.8^3 = 7.8 \times 7.8 \times 7.8\) Step 2: Calculate the answer. You get approximately 474.552 as the answer. Hence, the cube of 7.8 is approximately 474.552.

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Using a Formula (\(a^3\))

The formula \((a + b)^3\) is a binomial formula for finding the cube of a number. The formula is expanded as \(a^3 + 3a^2b + 3ab^2 + b^3\). Step 1: Split the number 7.8 into two parts. Let \(a = 7\) and \(b = 0.8\), so \(a + b = 7.8\). Step 2: Now, apply the formula \((a + b)^3 = a^3 + 3a^2b + 3ab^2 + b^3\). Step 3: Calculate each term. \(a^3 = 7^3\) \(3a^2b = 3 \times 7^2 \times 0.8\) \(3ab^2 = 3 \times 7 \times 0.8^2\) \(b^3 = 0.8^3\) Step 4: Add all the terms together: \((a + b)^3 = a^3 + 3a^2b + 3ab^2 + b^3\) \((7 + 0.8)^3 = 7^3 + 3 \times 7^2 \times 0.8 + 3 \times 7 \times 0.8^2 + 0.8^3\) \(7.8^3 = 343 + 117.6 + 13.44 + 0.512\) \(7.8^3 \approx 474.552\) Step 5: Hence, the cube of 7.8 is approximately 474.552.

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Using a Calculator

To find the cube of 7.8 using a calculator, input the number 7.8 and use the cube function (if available) or multiply \(7.8 \times 7.8 \times 7.8\). This operation calculates the value of \(7.8^3\), resulting in approximately 474.552. It’s a quick way to determine the cube without manual computation. Step 1: Ensure the calculator is functioning properly. Step 2: Press 7 followed by . Step 3: If the calculator has a cube function, press it to calculate \(7.8^3\). Step 4: If there is no cube function on the calculator, simply multiply 7.8 three times manually. Step 5: The calculator will display approximately 474.552.

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Tips and Tricks for the Cube of 7.8

The cube of any non-integer can be approximated using binomial expansion or calculator methods for greater accuracy. Cubing decimals can be simplified by converting them to fractions and then applying cube operations. A perfect cube can always be expressed as the product of three identical groups of equal factors.

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Common Mistakes to Avoid When Calculating the Cube of 7.8

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

Mistake 1

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Incorrect Multiplication

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Numbers might be multiplied only twice, such as \(7.8 \times 7.8\) and not \(7.8 \times 7.8 \times 7.8\). Always remember that \(7.8^3 = 7.8 \times 7.8 \times 7.8\).

Mistake 2

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Misunderstanding the Cube Formula

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There is a possibility of confusion between the formulas for square numbers and cube numbers. The square number formula is \((a + b)^2\) and the cube number formula is \((a + b)^3\). Always review the formulas to understand the difference between squaring and cubing.

Mistake 3

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Calculator Misuse

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There might be mistakes such as using the square (\(x^2\)) function instead of the cube (\(x^3\)) function or skipping steps in manual multiplication. Always double-check your inputs on the calculator, and if it lacks a cube function, perform the multiplication in steps.

Mistake 4

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Misplacing Decimals

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Misplacing decimals during manual multiplication leads to incorrect results. Double-check the placement of decimals to ensure accuracy.

Mistake 5

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Ignoring the Binomial Formula

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Attempting to split the number but not applying the correct binomial expansion. To avoid this, carefully calculate each term step-by-step during the application of the formula.

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Solved Examples on Cube of 7.8

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Problem 1

What is the cube and cube root of 7.8?

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The cube of 7.8 is approximately 474.552, and the cube root of 7.8 is approximately 1.965.

Explanation

First, let’s find the cube of 7.8. The cube of a number is given by \(x^3 = y\), where \(x\) is the number and \(y\) is the cubed value. So, \(7.8^3 \approx 474.552\). Next, we find the cube root of 7.8. The cube root of a number \(x\), denoted \(\sqrt[3]{x} = y\), gives the original number when cubed. So, \(\sqrt[3]{7.8} \approx 1.965\). Hence, the cube of 7.8 is approximately 474.552, and the cube root of 7.8 is approximately 1.965.

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Problem 2

If the side length of a cube is 7.8 cm, what is the volume?

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The volume is approximately 474.552 cm³.

Explanation

Use the volume formula for a cube \(V = \text{Side}^3\). Substitute 7.8 for the side length: \(V = 7.8^3 \approx 474.552 \text{ cm}^3\).

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Problem 3

How much larger is \(7.8^3\) than \(6.8^3\)?

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\(7.8^3 - 6.8^3 \approx 293.784\).

Explanation

First, find the cube of 7.8, which is approximately 474.552. Next, find the cube of 6.8, which is approximately 180.768. Now, find the difference between them using the subtraction method: \(474.552 - 180.768 \approx 293.784\). Therefore, \(7.8^3\) is approximately 293.784 larger than \(6.8^3\).

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Problem 4

If a cube with a side length of 7.8 cm is compared to a cube with a side length of 3 cm, how much larger is the volume of the larger cube?

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The volume of the cube with a side length of 7.8 cm is approximately 474.552 cm³.

Explanation

To find its volume, we multiply the side length by itself three times (since it’s a 3-dimensional object). Cubing 7.8 means multiplying 7.8 by itself three times: \(7.8 \times 7.8 = 60.84\), and then \(60.84 \times 7.8 \approx 474.552\). The unit of volume is cubic centimeters (cm³) because we are calculating the space inside the cube. Therefore, the volume of the cube is approximately 474.552 cm³.

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Problem 5

Estimate the cube of 7.9 using the cube of 7.8.

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The cube of 7.9 is approximately 493.039.

Explanation

First, identify the cube of 7.8, The cube of 7.8 is \(7.8^3 \approx 474.552\). Since 7.9 is only slightly larger than 7.8, the cube of 7.9 will be slightly more than the cube of 7.8. Calculating \(7.9^3\) gives approximately 493.039, reflecting the small increase from 7.8 to 7.9.

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FAQs on Cube of 7.8

1.What are the perfect cubes up to 7.8?

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2.How do you calculate \(7.8^3\)?

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3.What is the meaning of \(7.8^3\)?

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4.What is the cube root of 7.8?

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5.Is 7.8 a perfect cube?

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Important Glossaries for Cube of 7.8

Binomial Formula: An algebraic expression used to expand the powers of a number, written as \((a + b)^n\), where ‘n’ is a positive integer. 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: 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, \(2^3\) represents \(2 \times 2 \times 2\) equals 8. Decimal Multiplication: The process of multiplying decimal numbers, which involves careful placement of decimal points to ensure accuracy. Volume: The amount of space occupied by a 3-dimensional object, typically measured in cubic units. For cubes, the formula is \(V = \text{Side}^3\).

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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.

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Fun Fact

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

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