What is Cube Root? Meaning, Steps, and Solved Examples

The concept of cube root is a fundamental building block in mathematics, frequently appearing in school exams, competitive tests like JEE and NEET, and in real-life problem solving. Grasping the cube root is crucial for understanding number systems, exponents, and algebraic operations.

Understanding Cube Root

A cube root is a number that, when multiplied by itself three times (i.e., raised to the power of three), gives the original number. For any number \( a \), the cube root is written as \( \sqrt[3]{a} \) or ∛a. If \( b^3 = a \), then \( b \) is the cube root of \( a \). This idea is widely used in solving equations, understanding roots, and analyzing cube-shaped volumes.

Cube Root Symbol and Notation

The cube root symbol is ∛. For example, ∛27 means the cube root of 27. In equations, this is the same as raising a number to the power of one-third: \( a^{1/3} \). For example, ∛8 = 2, since \( 2^3 = 8 \).

Cube Root Formula

The general formula for the cube root is:

If \( y = x^3 \), then \( x = \sqrt[3]{y} \)

This means to find the cube root of \( y \), determine which number multiplied by itself three times gives \( y \).

Properties of Cube Root

• The cube root of 0 is 0: ∛0 = 0
• The cube root of 1 is 1: ∛1 = 1
• Cubes and cube roots of negative numbers are negative, e.g., ∛(-8) = -2
• Cube roots of perfect cubes are always integers
• For any real number, the cube root always exists (unlike square roots of negative numbers)

How to Calculate Cube Root

There are several ways to calculate the cube root of a number:

1. Prime Factorization Method: Find the prime factors and group them in sets of three. Multiply one prime from each set to get the cube root.
2. Estimation Method: Use the nearby perfect cubes to estimate and refine the answer.
3. Cube Root Table: Refer to a precomputed table of cubes and cube roots for quick results.
4. Calculator: Use a cube root calculator for large or non-perfect cubes.

For example, to find ∛216:

1. Prime factorize: 216 = 2 × 2 × 2 × 3 × 3 × 3
2. Groups: (2 × 2 × 2) and (3 × 3 × 3)
3. Take one from each group: 2 × 3 = 6
4. Answer: ∛216 = 6

Worked Examples

Here are some examples to help you understand cube roots better:

1. Find the cube root of 729.
   \( 729 = 9 \times 9 \times 9 = 9^3 \), so ∛729 = 9.
2. Find the cube root of 2744.
   \( 2744 = 2 \times 2 \times 2 \times 7 \times 7 \times 7 = (2 \times 7)^3 = 14^3 \), so ∛2744 = 14.
3. Find the cube root of -125.
   Since \( (-5)^3 = -125 \), ∛(-125) = -5.

Practice Problems

• Find ∛512
• Find the cube root of 8000
• Calculate ∛1000
• Find the cube root of -64
• Find the cube root of 343

Try these yourself before checking the answers below!

• ∛512 = 8
• ∛8000 = 20
• ∛1000 = 10
• ∛(-64) = -4
• ∛343 = 7

Common Mistakes to Avoid

• Confusing cube roots with square roots. Remember, cube rooting means finding a number multiplied three times, not just two.
• Forgetting that negative numbers have cube roots. The cube root of a negative number is negative.
• Not grouping prime factors in threes when using the factorization method.
• Assuming only perfect cubes have cube roots; every real number has a cube root (though it may be irrational).

Real-World Applications

Cube roots are used in fields like engineering, architecture, and science. For instance, when calculating the side of a cube given its volume (Volume = Side³), or in physics when dealing with scale models and density. At Vedantu, we often use cube roots in problems related to volumes, algebraic expressions, and practical applications in mathematics and science.

Learn more about cubes and cube roots in our topic Cubes and Cube Roots to deepen your understanding.

Cube Root Table (1 to 30)

You can also use our Cube Root Table Calculator for quick lookups.

Short Tricks & Tips

• Cubes ending with 1, 4, 5, 6, 9, and 0 have cube roots ending with the same digit.
• Memorize perfect cubes up to at least 20; this makes solving cube root problems quick in exams.
• For three-digit perfect cubes, observe the last digit for fast estimation (e.g., cubes ending in 8 have cube roots ending in 2).

At Vedantu, we simplify cube roots and other maths concepts to help you solve questions faster and with confidence. Explore more on related topics like Exponents & Powers, Prime Factorization, and Square Root Finder for deeper learning.

In this topic, we covered the definition of cube root, notation, calculation tricks, worked examples, and real-life applications. Mastering cube roots is essential for building your number sense, tackling algebraic expressions, and solving challenging problems in exams and beyond.