Square and Square Roots Lesson- Definition, Tables, Examples
Lesson Overview
What Are Squares and Square Roots?
A square is the result of multiplying a number by itself.
For example, 4 × 4 = 16, so 16 is the square of 4.
A square root is the number you multiply by itself to get the square.
For example, the square root of 16 is 4 because 4 × 4 = 16.
Square and Square Roots Table
Number (n) Square (n²) Square Root (√n) 1 1 1 2 4 1.41 3 9 1.73 4 16 2 5 25 2.24 6 36 2.45 7 49 2.65 8 64 2.83 9 81 3 10 100 3.16 11 121 3.32 12 144 3.46 13 169 3.61 14 196 3.74 15 225 3.87
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What Are Perfect Squares?
Perfect squares are numbers obtained by squaring whole numbers. Examples are:
1 is a perfect square because 1 × 1 = 1.
25 is a perfect square because 5 × 5 = 25.
64 is a perfect square because 8 × 8 = 64.
How to Find the Square
Finding the square of a number is simple. Follow these steps:
Understand what a square means
The square of a number is the result of multiplying that number by itself.
For example, if the number is 3, its square is 3 × 3 = 9.
Write the number twice
Take the number and write it down two times as a multiplication.
Example: To find the square of 5, write 5 × 5.
Multiply the number by itself
Perform the multiplication.
Example: 5 × 5 = 25. So, the square of 5 is 25.
Use a calculator if needed
If the number is large, use a calculator to make the multiplication faster and more accurate.
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Properties of Square Numbers
Property Description Example Non-Negativity Square numbers are always non-negative. (−3)2 = 9 32 = 9 Odd or Even Nature Squares of even numbers are even; squares of odd numbers are odd. 42 =16 (even) 52 = 25 (odd) End Digits A square number ends in 0,1,4,5,6, or 9; never 2,3,7, or 8. 62 = 36 72 = 49 Triangular Number Connection The sum of two consecutive triangular numbers is a square number. T3 +T4 = 6 + 10 = 16 = 42 Difference Between Squares Consecutive square numbers differ by consecutive odd numbers. 52 − 42 = 25 − 16 = 9 (an odd number) Sum of First n Odd Numbers The sum of the first n odd numbers equals n 2 . 1 + 3 + 5 = 9 = 32
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Solved Examples on Squares and Square Roots
Example 1: Find the square of 7. Solution:
The square of a number is obtained by multiplying the number by itself.
Square of 7 = 7 × 7 = 49.
Answer: 49
Example 2: Find the square root of 81. Solution:
The square root is the number which, when multiplied by itself, gives the square.
We know 9 × 9 = 81.
Therefore, the square root of 81 is 9.
Answer: 9
Example 3: Check if 36 is a perfect square. Solution:
A number is a perfect square if it can be expressed as the square of a whole number.
Find the square root of 36.
6 × 6 = 36, so the square root of 36 is 6.
Since the square root is a whole number, 36 is a perfect square.
Answer: Yes, 36 is a perfect square.
Example 4: Calculate the square of 15 and explain if it is even or odd. Solution:
Square of 15 = 15 × 15 = 225.
15 is an odd number, and the square of an odd number is always odd.
Answer: 225 (odd number).
Example 5: Find the square root of 144 and verify the result. Solution:
The square root of 144 is the number that, when multiplied by itself, equals 144.
12 × 12 = 144, so the square root of 144 is 12.
Verification: 12 × 12 = 144 (Correct).
Answer: 12
Square and Square Roots Assessments
Write the squares of numbers 1 to 15.
Find the square roots of 1, 16, 81, and 100.
Check whether 49 and 72 are perfect squares by finding their square roots.
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