Last updated on May 26th, 2025
If a number is multiplied by itself, the result is a square. The inverse of the square is a square root. The square root is used in various fields such as vehicle design, finance, etc. Here, we will discuss the square root of 405.
The square root is the inverse of the square of a number. 405 is not a perfect square. The square root of 405 is expressed in both radical and exponential form. In the radical form, it is expressed as √405, whereas (405)^(1/2) in the exponential form. √405 ≈ 20.1246, which is an irrational number because it cannot be expressed in the form of p/q, where p and q are integers and q ≠ 0.
The prime factorization method is used for perfect square numbers. However, for non-perfect square numbers like 405, the long division method and approximation method are used. Let us now learn the following methods:
The product of prime factors is the prime factorization of a number. Now let us look at how 405 is broken down into its prime factors.
Step 1: Finding the prime factors of 405 Breaking it down, we get 3 x 3 x 3 x 3 x 5: 3^4 x 5
Step 2: Now we found the prime factors of 405. The second step is to make pairs of those prime factors. Since 405 is not a perfect square, the digits of the number can’t be grouped in pairs completely.
Therefore, calculating √405 using prime factorization alone does not yield an exact result.
The long division method is particularly used for non-perfect square numbers. In this method, we should check the closest perfect square number for the given number. Let us now learn how to find the square root using the long division method, step by step.
Step 1: To begin with, group the numbers from right to left. In the case of 405, group it as 05 and 4.
Step 2: Find n whose square is less than or equal to 4. We can say n is '2' because 2 x 2 = 4. Now the quotient is 2 and the remainder is 0.
Step 3: Bring down 05, which is the new dividend. Add the old divisor with the same number (2 + 2 = 4), which will be our new divisor.
Step 4: The new divisor will be 4n. We need to find the value of n such that 4n x n ≤ 05. Let us consider n as 1, now 4 x 1 x 1 = 4.
Step 5: Subtract 5 from 4, the difference is 1.
Step 6: Since the dividend is less than the divisor, we add a decimal point and bring down two zeros, making the new dividend 100.
Step 7: Find the new divisor, which is 41. Use 41n x n ≤ 100. Let n be 2, then 41 x 2 x 2 = 164, which doesn't fit. Try n = 1, and 41 x 1 x 1 = 41.
Step 8: Subtract 41 from 100, the remainder is 59, and the quotient becomes 20.1.
Step 9: Continue these steps for more precision until you get the desired number of decimal places.
So the square root of √405 ≈ 20.12
The approximation method is another method for finding square roots. It is an easy method to find the square root of a given number. Let us learn how to find the square root of 405 using the approximation method.
Step 1: Identify the closest perfect squares to √405. The nearest perfect squares are 400 and 441. √405 falls between 20 and 21.
Step 2: Apply the formula: (Given number - smallest perfect square) / (Greater perfect square - smallest perfect square) Using the formula: (405 - 400) / (441 - 400) = 5 / 41 ≈ 0.122 Add the initial integer value to the decimal: 20 + 0.122 ≈ 20.122
Thus, the square root of 405 is approximately 20.12.
Students often make mistakes while finding the square root, such as forgetting about the negative square root or skipping steps in the long division method. Let us look at a few common mistakes in detail.
Can you help Max find the area of a square box if its side length is given as √405?
The area of the square is 405 square units.
The area of a square = side^2. The side length is given as √405.
Area = side^2 = √405 x √405 = 405
Therefore, the area of the square box is 405 square units.
A square-shaped building measuring 405 square feet is built; if each of the sides is √405, what will be the square feet of half of the building?
202.5 square feet
We can divide the given area by 2 as the building is square-shaped.
Dividing 405 by 2 = 202.5 So half of the building measures 202.5 square feet.
Calculate √405 x 5.
100.62
First, find the square root of 405, which is approximately 20.12.
Then multiply 20.12 by 5. 20.12 x 5 = 100.62
What will be the square root of (400 + 5)?
The square root is approximately 20.12
To find the square root, calculate (400 + 5) = 405.
The square root of 405 is approximately 20.12.
Therefore, the square root of (400 + 5) is approximately ±20.12.
Find the perimeter of the rectangle if its length ‘l’ is √405 units and the width ‘w’ is 30 units.
The perimeter of the rectangle is approximately 100.24 units.
Perimeter of the rectangle = 2 × (length + width)
Perimeter = 2 × (√405 + 30) ≈ 2 × (20.12 + 30)
Perimeter ≈ 2 × 50.12 = 100.24 units.
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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