Mathematics Grade 7 15 min

Estimate square roots

Estimate square roots

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Introduction & Learning Objectives

Learning Objectives Define perfect squares and non-perfect squares. Identify perfect squares up to 150. Locate a non-perfect square between two consecutive perfect squares. Estimate the square root of a non-perfect square to the nearest whole number. Explain the reasoning behind their square root estimations. Use a number line to visualize the estimation of square roots. Imagine you need to build a square garden with an area of 50 square feet. How long would each side be? 🤔 It's not a whole number, so we need to estimate! In this lesson, you'll learn how to estimate the square roots of numbers that aren't perfect squares. This skill is super useful for quick calculations and understanding the approximate size of numbers without needing a calculator, helping...
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Key Concepts & Vocabulary

TermDefinitionExample SquareThe result of multiplying a number by itself. For example, the square of 5 is $5 \times 5 = 25$.The square of 8 is $8^2 = 64$. Square RootA number that, when multiplied by itself, gives the original number. It's the inverse operation of squaring a number.The square root of 49 is 7, because $7 \times 7 = 49$. We write this as $\sqrt{49} = 7$. Perfect SquareA number whose square root is a whole number (an integer).1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144 are all perfect squares. Non-Perfect SquareA number whose square root is not a whole number. Its square root is an irrational number (a decimal that goes on forever without repeating).2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15 are all non-perfect squares. EstimationFinding an approximate value that is cl...
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Core Formulas

Definition of a Square Root If $n^2 = x$, then $n$ is a square root of $x$. The principal (positive) square root is denoted by $\sqrt{x}$. This rule defines what a square root is. For example, since $6^2 = 36$, then $\sqrt{36} = 6$. We focus on the positive square root in Grade 7. Identifying Perfect Squares A number $x$ is a perfect square if its square root, $\sqrt{x}$, is an integer. To identify perfect squares, you can list numbers and their squares: $1^2=1, 2^2=4, 3^2=9, \dots$. These squared numbers are the perfect squares. Estimating Non-Perfect Square Roots To estimate $\sqrt{x}$ where $x$ is a non-perfect square, find two consecutive perfect squares, $a^2$ and $b^2$, such that $a^2 < x < b^2$. Then, $a < \sqrt{x} < b$. This rule helps you 't...

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Sample Practice Questions

Challenging
A square garden has an area of 40 square feet. A gardener wants to place a decorative border around the entire perimeter of the garden. Which is the best estimate for the total length of the border needed?
A.12 feet
B.18 feet
C.24 feet
D.32 feet
Challenging
Consider the number 150. Its square root is between 12 (√144) and 13 (√169). Which statement is most accurate?
A.The square root of 150 is closer to 12 because 150 is only 6 away from 144, while it is 19 away from 169.
B.The square root of 150 is closer to 13 because 150 is a large number.
C.The square root of 150 is exactly 12.5 because 150 is about halfway between 144 and 169.
D.The square root of 150 is closer to 13 because 150 is closer to 169 than it is to 144.
Easy
Which of the following best defines a 'perfect square'?
A.number whose square root is a whole number.
B.Any number that is multiplied by 2.
C.number that has only two factors.
D.number whose square root is a decimal.

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