Square of 4.2
2026-02-28 10:27 Diff
https://brightchamps.com/en-us/math/algebra/square-of-4.2

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Last updated on August 5, 2025

The product of multiplying a number by itself is the square of that number. Square is used in programming, calculating areas, and so on. In this topic, we will discuss the square of 4.2.

What is the Square of 4.2

The square of a number is the product of the number itself. The square of 4.2 is 4.2 × 4.2. The square of a number often ends in 0, 1, 4, 5, 6, or 9. We write it in math as \(4.2^2\), where 4.2 is the base and 2 is the exponent. The square of a positive and a negative number is always positive. For example, \(5^2 = 25\); \((-5)^2 = 25\). The square of 4.2 is 4.2 × 4.2 = 17.64. Square of 4.2 in exponential form: \(4.2^2\) Square of 4.2 in arithmetic form: 4.2 × 4.2

How to Calculate the Value of Square of 4.2

The square of a number is multiplying the number by itself. So let’s learn how to find the square of a number. These are the common methods used to find the square of a number. By Multiplication Method Using a Formula Using a Calculator

By the Multiplication method

In this method, we will multiply the number by itself to find the square. The product here is the square of the number. Let’s find the square of 4.2 Step 1: Identify the number. Here, the number is 4.2 Step 2: Multiplying the number by itself, we get, 4.2 × 4.2 = 17.64. The square of 4.2 is 17.64.

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Using a Formula (\(a^2\))

In this method, the formula, \(a^2\) is used to find the square of the number. Where \(a\) is the number. Step 1: Understanding the equation Square of a number = \(a^2\) \(a^2 = a \times a\) Step 2: Identifying the number and substituting the value in the equation. Here, ‘a’ is 4.2 So: \(4.2^2 = 4.2 \times 4.2 = 17.64\)

By Using a Calculator

Using a calculator to find the square of a number is the easiest method. Let’s learn how to use a calculator to find the square of 4.2. Step 1: Enter the number in the calculator Enter 4.2 in the calculator. Step 2: Multiply the number by itself using the multiplication button (×) That is 4.2 × 4.2 Step 3: Press the equal to button to find the answer Here, the square of 4.2 is 17.64. Tips and Tricks for the Square of 4.2 Tips and tricks make it easy for students to understand and learn the square of a number. To master the square of a number, these tips and tricks will help students. The square of an even number is always an even number. For example, \(6^2 = 36\) The square of an odd number is always an odd number. For example, \(5^2 = 25\) The last digit of the square of a number is always 0, 1, 4, 5, 6, or 9. If the square root of a number is a fraction or a decimal, then the number is not a perfect square. For example, \(\sqrt{1.44} = 1.2\) The square root of a perfect square is always a whole number. For example, \(\sqrt{144} = 12\).

Common Mistakes to Avoid When Calculating the Square of 4.2

Mistakes are common among kids when doing math, especially when it is finding the square of a number. Let’s learn some common mistakes to master the squaring of a number.

Problem 1

Find the length of the square, where the area of the square is 17.64 cm².

Okay, lets begin

The area of a square = \(a^2\) So, the area of a square = 17.64 cm² So, the length = \(\sqrt{17.64} = 4.2\). The length of each side = 4.2 cm

Explanation

The length of a square is 4.2 cm. Because the area is 17.64 cm², the length is \(\sqrt{17.64} = 4.2\).

Well explained 👍

Problem 2

Alice is planning to paint her square wall of length 4.2 feet. The cost to paint a foot is 5 dollars. Then how much will it cost to paint the full wall?

Okay, lets begin

The length of the wall = 4.2 feet The cost to paint 1 square foot of wall = 5 dollars. To find the total cost to paint, we find the area of the wall, Area of the wall = area of the square = \(a^2\) Here \(a = 4.2\) Therefore, the area of the wall = \(4.2^2 = 4.2 \times 4.2 = 17.64\). The cost to paint the wall = 17.64 × 5 = 88.2. The total cost = 88.2 dollars

Explanation

To find the cost to paint the wall, we multiply the area of the wall by the cost to paint per foot. So, the total cost is 88.2 dollars.

Well explained 👍

Problem 3

Find the area of a circle whose radius is 4.2 meters.

Okay, lets begin

The area of the circle = 55.42 m²

Explanation

The area of a circle = πr² Here, r = 4.2 Therefore, the area of the circle = π × \(4.2^2\) = 3.14 × 4.2 × 4.2 = 55.42 m².

Well explained 👍

Problem 4

The area of the square is 17.64 cm². Find the perimeter of the square.

Okay, lets begin

The perimeter of the square is 16.8 cm

Explanation

The area of the square = \(a^2\) Here, the area is 17.64 cm² The length of the side is \(\sqrt{17.64} = 4.2\) Perimeter of the square = 4a Here, a = 4.2 Therefore, the perimeter = 4 × 4.2 = 16.8 cm.

Well explained 👍

Problem 5

Find the square of 5.3.

Okay, lets begin

The square of 5.3 is 28.09

Explanation

The square of 5.3 is multiplying 5.3 by 5.3. So, the square = 5.3 × 5.3 = 28.09

Well explained 👍

FAQs on Square of 4.2

1.What is the square of 4.2?

The square of 4.2 is 17.64, as 4.2 × 4.2 = 17.64.

2.What is the square root of 4.2?

The square root of 4.2 is approximately ±2.05.

3.Is 4.2 a rational number?

Yes, 4.2 is a rational number because it can be expressed as a fraction \(\frac{42}{10}\).

4.What are the first few multiples of 4.2?

The first few multiples of 4.2 are 4.2, 8.4, 12.6, 16.8, 21, 25.2, 29.4, 33.6, and so on.

5.What is the square of 5?

The square of 5 is 25, as 5 × 5 = 25.

Important Glossaries for Square of 4.2.

Rational number: A number that can be expressed as a fraction with integer numerator and a non-zero integer denominator. For example, 4.2 can be expressed as \(\frac{42}{10}\). Exponential form: Exponential form is the way of writing a number in the form of a power. For example, \(4.2^2\) where 4.2 is the base and 2 is the power. Square root: The square root is the inverse operation of the square. The square root of a number is a number whose square is the number itself. Perimeter: The total length of the sides of a two-dimensional shape. For a square, it is calculated as 4 times the length of one side. Area: The amount of space enclosed within a shape. For a square, it is calculated as the side length squared.

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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.