Perfect Squares

Last Updated: June 19, 2024

Perfect Squares

What is Perfect Squares?

A perfect square is an integer that is the square of an integer. In other words, it is the product of some integer with itself. For example, 16 is a perfect square because it is 4 times 4.

Perfect Square Formula

perfect squares are numbers that can be expressed as a product of an integer with itself which ultimately gives us the square of that integer.

P = n × n =n²

Perfect Squares List

Below, you’ll find a comprehensive list of perfect squares ranging from 1 to 100, accompanied by their factors, which are essentially the product of integers.


Perfect Squares List

Below is a table of perfect squares, detailing the squares of numbers ranging from 1 to 50.

Perfect Squares List

From this analysis, we uncover the formula that reveals the difference between any perfect square and its immediate predecessor. This relationship is encapsulated in the formula:

n² − (n − 1)² = 2n − 1

Additionally, we can calculate the number of square numbers utilizing the formula:

n² = (n − 1)² + (n − 1) + n

Perfect Square Example

Algebraic identities as perfect squares:

a² + 2ab + b² = (a + b)²

a² – 2ab + b² = (a – b)²

Polynomials as perfect squares:

Let us take the polynomial x² + 6x + 9.

Now, factorise the polynomial.

x² + 6x + 9 = x² + 3x + 3x + 9

= x(x + 3) + 3(x + 3)

= (x + 3)(x + 3)

= (x + 3)²

Above examples, we can say that x²+ 6x + 9 is called perfect square trinomials.

Perfect Squares Chart

Tips and Tricks to Find Perfect Squares

Occasionally, it’s possible to identify the perfect squares of certain numbers without resorting to the lengthy process of long multiplication.

Example 1: Numbers ending with the digit 5

First, divide the two-digit number into its individual digits. Multiply the digit in the tens place by the next consecutive number. Then, take the digit in the units place and square it. Combine these two outcomes to form your result: 85²

Example 2: Using the formula  a² + 2ab + b² = (a + b)²

To calculate the square of large numbers, you can decompose them into more manageable numbers using the aforementioned formula and subsequently expand the expression.

87² = (80+7)²= 80²+ 2.80.7 + 7² = 6400 + 1120 + 49 = 7569

Facts about Perfect Squares

  • If a number ends in zero, squaring that number will always result in an even number of zeros at the end.
  • Square roots of negative numbers are undefined, as there are no negative perfect squares.
  • The area of a square with side length “s” is calculated by the formula:
  • The principal square root of a number is its positive square root. Typically, “the square root” of a number refers to this principal, or positive, square root.

How to Identify Perfect Squares

  1. Understand the Definition: A perfect square is the product of an integer multiplied by itself. For example, 16 is a perfect square because it is 4×4.
  2. Look for Familiar Patterns: Familiarize yourself with the first few perfect squares: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, and so on. Notice patterns, such as how every perfect square ends with 1, 4, 6, 9, or 00 in the decimal system
  3. Use Digital Roots: Digital roots can sometimes help in identifying perfect squares. The digital root of a number is the sum of its digits, and this process is repeated until a single digit is obtained. For perfect squares, digital roots are always 1, 4, 7, or 9. This isn’t a foolproof method but can be a helpful clue.
  4. Employ the Modulo Operation: In a more technical approach, certain modulo operations (remainder after division) can hint at a perfect square. For instance, a perfect square modulo 1010 can only result in 0, 1, 4, 5, 6, or 9.
  5. Square Root Test: The most definitive way to identify a perfect square is to find its square root. If the square root of a number is an integer, then the number is a perfect square. This can be done using a calculator for large numbers.
  6. Memorize Small Squares: Knowing the squares of numbers at least up to 12 (i.e., 144) by heart can help you quickly identify larger perfect squares, as they are often multiples of these smaller squares.
  7. Look for Patterns in Prime Factorization: Perfect squares have an even number of each prime factor. For example, 36=2²×3². This means that if you can factor a number and all prime factors appear an even number of times, the number is a perfect square.

Questions & Answers for Practice

Short Question

Q1: Is 49 a perfect square?

A1: Yes, 49 is a perfect square because 7×7=49

Q2: What is the next perfect square after 16?

A2: The next perfect square after 16 is 25, because 5×5=25

Q3: Find the square of 8.

A3: The square of 8 is 8×8=64

Q4: Express 121 as a product of an integer with itself.

A4: 121 can be expressed as 11×11

Q5: Which of the following is a perfect square: 18, 36, 52?

A5: 36 is a perfect square (6×6=36).

Q6: Calculate the square of 15.

A6: The square of 15 is 15×15=225

Q7: Is 144 a perfect square? If so, find its square root.

A7: Yes, 144 is a perfect square. Its square root is 12 ,(12×12=144).

 Q8: Find the perfect square of 18 using the formula (a + b)² = a² + 2ab + b² 

Solution:  We will split 18 as (10+8) to use the formula.

Solution:  We will split 18 as (10+8) to use the formula.

18 x 18 = 18²

= (10+8)² ……….(a + b)²

= 100 + 160 + 64 ………….. (a + b)² = a² + 2ab + b² 



What are the 4 Perfect Squares?

The first 4 perfect squares are 1 (1²), 4 (2²), 9 (3²), and 16 (4²). These numbers represent the squares of the first four positive integers.

What are the Perfect Squares 1 to 12?

The perfect squares from 1 to 1² are 1 (1²), 4 (2²), 9 (3²), 16 (4²), 25 (5²), 36 (6²), 49 (7²), 64 (8²), 81 (9²), 100 (10²), 121 (11²), and 144 (12²).

What is 20 Perfect Squares?

“20 perfect squares” refers to the square of the number 20, which is 20²=400. However, the term might also be misunderstood as asking for a list of 20 perfect square numbers, which would start from 1² and go up to 20².

Are 64 and 20 Perfect Squares?

Yes, 64 is a perfect square because it is 82. However, 20 is not a perfect square because there is no integer that, when squared, equals 20

In conclusion, perfect squares are fundamental in mathematics, representing numbers that are the product of an integer multiplied by itself. Understanding and identifying them enriches number theory knowledge and enhances problem-solving skills.

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