Tuesday, May 28, 2024

Finding the Square Root: Long Division and Prime Factorization Methods

Finding the Square Root


The square root is a fundamental concept in mathematics, which has extensive applications in various fields like physics, engineering, economics, computing, and even in our everyday life. It is the value that, when multiplied by itself, gives the original number. But how do we find this value? Two popular methods are the Long Division Method and the Prime Factorization Method. This blog post will delve into both methods, equipping you with the tools to unravel the mystery of square roots.

Long Division Method

The Long Division Method is a traditional approach to find the square root of a perfect square. It’s a step by step procedure which closely resembles the long division algorithm we use for dividing large numbers. Let’s look at how to use it.

  1. Group the digits of the number in pairs, starting from the rightmost side.
  2. Start dividing from the leftmost group. Find a number whose square is less than or equal to the leftmost group.
  3. Subtract the square of the number from the leftmost group and bring down the next pair.
  4. Double the divisor and write it with a blank on its right.
  5. Guess a digit to fill the blank which will also become a part of the quotient, such that when the new divisor is multiplied by this new digit, it is less than or equal to the current dividend.
  6. Repeat steps 3 to 5 until you have brought down all the pairs.


Let’s find square root of 529.

  1. Grouping from right, we get (5)(29)
  2. The largest number whose square is less than or equal to 5 is 2. So, 2 is the first digit of the root, and 4 (2*2) is subtracted from 5.
  3. After subtraction, we bring down the next pair i.e. 29. The number now becomes 129.
  4. The divisor now becomes 20 (double of 2 and leave one digit space on its right). We need to find a digit such that when the new divisor is multiplied by this digit, it should be less than or equal to 129. Here, the digit is 3 (23*3=69).
  5. Subtract 69 from 129 to get 60. As there are no more pairs left, we stop here.

So, the square root of 529 is 23.

Prime Factorization Method

The Prime Factorization Method involves breaking down the number into its prime factors and grouping them in pairs. Here’s how this method works.

  1. Write down the number as a product of its prime factors.
  2. Make pairs of similar factors.
  3. For each pair, choose one factor and multiply these chosen factors to get the square root.


Let’s find the square root of 784.

  1. Prime factorization of 784 = 2 x 2 x 2 x 2 x 7 x 7
  2. Making pairs of similar factors, we get (2 x 2), (2 x 2), (7 x 7)
  3. Choose one number from each pair. The chosen numbers are 2, 2, and 7.
  4. The square root of 784 is 2 x 2 x 7 = 28.

Comparison of Methods

Both methods have their pros and cons. The Long Division method is more versatile, as it can be used to find the square root of any number with precision, but it can be time-consuming for large numbers. On the other hand, the Prime Factorization method is quicker and simpler, but it’s only effective for perfect squares.


Understanding how to find the square root of a number is a vital part of one’s mathematical journey. The Long Division Method and the Prime Factorization Method are both effective strategies, each with unique benefits. By understanding these methods, practicing them, and knowing when to use each, you can enhance your mathematical skills and approach problems with greater confidence. So, keep practicing, and remember that every aspect of learning mathematics is another step forward in your journey of logical reasoning and problem-solving. Happy calculating!

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