Grade 8
Course ContentSquares/Roots
Habari Mwanafunzi! Let's Unlock the Power of Squares and Square Roots!
Welcome to another exciting Mathematics lesson! Today, we are going to tackle a topic that is everywhere around us, from the tiles on the floor to the way a farmer plants crops in a shamba. We're talking about Squares and Square Roots. Don't worry, by the end of this, you will be a master, ready to solve any problem that comes your way, even in a KCSE paper! Let's begin!
What is a 'Square' of a Number?
Imagine you have a number, say 5. To "square" this number simply means to multiply it by itself. That's it! It's like asking, "If I have a square plot of land with 5 metres on one side, what is its total area?" You'd multiply the side by itself.
We write the square of a number with a small '2' at the top right, which we call an exponent or a power. So, "5 squared" is written as 5².
5² = 5 x 5 = 25
Kenyan Example: Arranging Chairs
Think about setting up for a school assembly. If the headteacher wants a perfect square formation of chairs and asks for 10 rows, you will naturally put 10 chairs in each row. How many chairs in total? You've got it!
10 rows x 10 chairs per row = 10² = 100 chairs
Numbers that are the result of squaring a whole number (like 4, 9, 16, 25) are special. We call them perfect squares. It's very helpful to know the first few by heart:
- 1² = 1
- 2² = 4
- 3² = 9
- 4² = 16
- 5² = 25
- 6² = 36
- 7² = 49
- 8² = 64
- 9² = 81
- 10² = 100
- 11² = 121
- 12² = 144
Image Suggestion: A vibrant, colourful digital illustration of a Kenyan farmer, Mzee Juma, smiling on his 'shamba'. The shamba is a perfect square grid with 8 rows and 8 columns of healthy green sukuma wiki (kale) plants. The sun is shining brightly.
Now, Let's Go Backwards: Finding the Square Root!
The square root is the opposite of squaring. It's like asking, "I have 49 plants arranged in a perfect square. How many plants are in one row?" You are looking for the number that, when multiplied by itself, gives you 49.
The symbol for the square root is called a radical sign: √
We know 7 x 7 = 49
So, the square root of 49 is 7.
√49 = 7
For your exams (especially Paper 1 where calculators may not be allowed for certain questions), knowing how to find a square root by hand is a super skill. The best method is Prime Factorisation.
Let's find the square root of 784.
Step 1: Break down 784 into its prime factors using the division method.
2 | 784
--|----
2 | 392
--|----
2 | 196
--|----
2 | 98
--|----
7 | 49
--|----
7 | 7
--|----
| 1
So, 784 = 2 x 2 x 2 x 2 x 7 x 7
Step 2: Group the identical factors into pairs.
784 = (2 x 2) x (2 x 2) x (7 x 7)
Step 3: From each pair, pick only ONE number.
From (2 x 2) we pick 2.
From (2 x 2) we pick 2.
From (7 x 7) we pick 7.
Step 4: Multiply the numbers you picked. This is your answer!
√784 = 2 x 2 x 7 = 28
You can check your answer: Does 28 x 28 = 784? Yes, it does! You've done it!
Image Suggestion: A clear, step-by-step educational diagram showing the prime factorization of the number 144. It should show the division ladder on the left, the grouping of prime factors ( (2x2) x (2x2) x (3x3) ) in the middle, and the final multiplication (2 x 2 x 3 = 12) on the right.
What About Fractions and Decimals? No Problem!
The same rules apply, just with one extra step. Don't panic when you see them!
For Fractions: Find the square or square root of the numerator and the denominator separately.
Squaring a fraction:
(4/5)² = (4² / 5²) = 16/25
Finding the square root of a fraction:
√(36/81) = (√36 / √81) = 6/9 (which can be simplified to 2/3)
For Decimals: You can either convert the decimal to a fraction first, or follow this simple rule.
- Squaring: The answer will have double the number of decimal places.
(0.3)² = 0.3 x 0.3 = 0.09 (One decimal place becomes two) - Square Root: The answer will have half the number of decimal places.
√0.04 = √ (4/100) = (√4 / √100) = 2/10 = 0.2 (Two decimal places become one)
Kazi ya Mwalimu: Let's Solve a Problem!
Here is a typical question you might encounter. Let's solve it together.
The area of a square playing field in a school in Kisumu is 1296 square metres. The school wants to put a fence around it. What is the length of one side of the field?
To solve this, we need to find the number that, when multiplied by itself, gives 1296. That's the square root!
Let's use our prime factorisation method for √1296:
2 | 1296
--|-----
2 | 648
--|-----
2 | 324
--|-----
2 | 162
--|-----
3 | 81
--|-----
3 | 27
--|-----
3 | 9
--|-----
3 | 3
--|-----
| 1
Factors: (2 x 2) x (2 x 2) x (3 x 3) x (3 x 3)
Pick one from each pair: 2 x 2 x 3 x 3
Multiply: 4 x 9 = 36
The length of one side of the field is 36 metres.
See? You can handle any number, no matter how big!
+--------------+
| |
| |
36m | Area = |
| 1296 m² |
| |
+--------------+
36m
You've Got This! Wewe ni Msharp!
Congratulations! You have just mastered the essentials of squares and square roots. Remember these key points:
- To square a number, you multiply it by itself.
- The square root is the opposite; it's the base number that was multiplied to get the square.
- The prime factorisation method is your most reliable tool for finding square roots without a calculator.
Keep practicing these concepts. The more you practice, the faster and more confident you will become. You are building a strong foundation for more advanced topics in Mathematics. Keep up the great work!
Habari Mwanafunzi! Welcome to the World of Squares and Roots!
Have you ever seen a farmer planting sukuma wiki in a perfectly neat, square shamba? Or maybe you've played a game of drafts (or chess) on a board with an equal number of rows and columns? The secret behind these perfect shapes is today's topic in Mathematics: Squares and Square Roots! It might sound complex, but I promise you, by the end of this lesson, you will see them everywhere. Tuko pamoja? Let's begin!
What is a "Square" of a Number?
In mathematics, "squaring" a number is very simple: it just means multiplying a number by itself. That's it! We use a small '2' at the top right of the number to show we are squaring it. We call this 'to the power of 2'.
Formula:
n² = n × n
Think of it like finding the area of a square piece of land. If one side is 3 metres, the other side is also 3 metres. The area would be 3 × 3 = 9 square metres.
Let's look at this visually:
Here is a square with sides of length 3:
*--*--* (3 units)
| | |
*--*--*
| | |
*--*--*
| | |
*--*--*
(3 units)
If you count the small square boxes inside, you will find 9 of them.
So, 3² = 3 × 3 = 9
Kenyan Example: Imagine you are buying a square mat for your room. The shopkeeper tells you it is "2 by 2 metres". To find its area, you square the number 2.Area = 2m × 2m = 4 square metres. So, 2² = 4.
Numbers like 4, 9, 16, 25, 36, and so on, are special. They are called Perfect Squares because they are the result of squaring a whole number.
So, What is a "Square Root"?
Now, let's go backwards! A square root is the opposite of squaring. It's the number that you multiplied by itself to get the big number.
The symbol for square root looks like a little tick: √
So, if 5² = 25, then the square root of 25 is √25 = 5.
It's like asking the question: "Which number, when multiplied by itself, gives me 25?" The answer is 5!
Image Suggestion: A vibrant, colourful digital illustration of a Kenyan farmer standing proudly next to a perfectly square 'shamba' (farm) filled with rows of sukuma wiki. An overlay text on the shamba says "Area = 49m²". Another text bubble points to one side of the shamba with a large question mark, asking "Length = ? metres". The style should be friendly and educational.
How to Find the Square Root
For small numbers, you might know the answer from memory. But for larger numbers, like finding the square root of 324, we need a method! The most reliable one is using Prime Factorization.
Let's find the square root of 144 (√144) together. Follow these steps:
- Break it down: Find the prime factors of the number.
- Pair them up: Group the identical factors into pairs.
- Pick one from each pair: For every pair you made, take out only one number.
- Multiply: Multiply the numbers you picked. The result is your square root!
Let's try it with 144:
Step 1: Prime Factorization of 144
2 | 144
2 | 72
2 | 36
2 | 18
3 | 9
3 | 3
| 1
So, 144 = 2 × 2 × 2 × 2 × 3 × 3
Step 2: Group the factors into pairs
144 = (2 × 2) × (2 × 2) × (3 × 3)
Step 3: Pick one from each pair
From the first pair we pick one '2'.
From the second pair we pick another '2'.
From the third pair we pick one '3'.
Step 4: Multiply them together
Result = 2 × 2 × 3 = 12
Therefore, the square root of 144 is 12! (√144 = 12)
Real-Life Scenario: The headteacher at Baraka High School wants to arrange all 225 Form One students in a perfect square for an assembly drill. How many students should be in each row to make this happen?To solve this, the headteacher needs to find the square root of 225!
Using prime factorization: 225 = (3 × 3) × (5 × 5).
We pick one '3' and one '5'.
3 × 5 = 15.
So, the students should be arranged in 15 rows with 15 students in each row. Sawa?
Let's Recap!
Wow, you have learned so much today! Let's summarise the key points:
- Squaring a number means multiplying it by itself (e.g., 8² = 8 × 8 = 64).
- A Perfect Square is the result of squaring a whole number (e.g., 64).
- A Square Root (√) is the reverse of squaring. It's the number that was multiplied by itself to get the result (e.g., √64 = 8).
- You can find the square root of large numbers using the prime factorization method.
Mathematics is like a great adventure. Every topic you learn is a new tool in your backpack. Keep practicing, stay curious, and you will be able to solve any problem that comes your way. Hongera sana for your hard work today!
Habari Mwanafunzi! Let's Conquer Squares and Square Roots!
Welcome, future mathematician! Today, we are going to explore a very exciting part of numbers that is all around us, from the shape of a mandazi to the way a farmer plants crops in a shamba (farm). This topic is called Squares and Square Roots. By the end of this lesson, you will be a champion at it. Let's begin!
What in the World is a 'Square Number'?
Have you ever seen a perfect square? Maybe a tile on the floor or a window pane? A square has all sides equal. In mathematics, a square number is what you get when you multiply a number by itself.
Imagine you are planting sukuma wiki. If you plant 3 rows and each row has 3 plants, you have a perfect square arrangement!
How many plants do you have in total? You have 3 x 3 = 9 plants. So, 9 is a square number!
* * * (3 plants in a row)
* * * (3 plants in a row)
* * * (3 plants in a row)
3 rows of 3 = 3 x 3 = 9
We write this as 3², which we read as "three squared". The small '2' tells us to multiply the number by itself two times.
- 1² = 1 x 1 = 1
- 2² = 2 x 2 = 4
- 3² = 3 x 3 = 9
- 4² = 4 x 4 = 16
- 5² = 5 x 5 = 25
- ...and so on!
These numbers (1, 4, 9, 16, 25) are all special; they are called perfect squares.
Image Suggestion: [A vibrant, top-down photograph of a neatly planted Kenyan shamba. The farm is divided into perfect square plots. In one plot, a farmer is planting sukuma wiki seedlings in a perfect 5x5 grid. The sun is bright, and the soil is a rich, dark red.]
Okay, So What is a 'Square Root'?
Now, let's work backwards! A square root is the opposite of squaring a number. If I tell you I have a square shamba with 25 maize plants in total, can you tell me how many plants are in one row?
You are looking for a number that, when multiplied by itself, gives you 25. That number is 5! (Because 5 x 5 = 25). So, the square root of 25 is 5.
We use a special symbol for the square root, which looks like a "tick" mark. It is called the radical symbol: √
We know: 5² = 25
So, the opposite is: √25 = 5
Finding the square root is like asking: "Which number was multiplied by itself to get this result?"
How to Find Square Roots (The Mwalimu's Method)
For big numbers, we can't just guess. We need a solid method! The most common one is using Prime Factorization. Don't worry, it's easier than it sounds.
Example: Let's find the square root of 144 (√144).
Step 1: Break down 144 into its prime factors. A prime number is a number that can only be divided by 1 and itself (like 2, 3, 5, 7, 11...). We can use a factor tree.
144
/ \
2 72
/ \
2 36
/ \
2 18
/ \
2 9
/ \
3 3
So, the prime factors are: 2, 2, 2, 2, 3, 3
144 = 2 x 2 x 2 x 2 x 3 x 3
Step 2: Pair up the identical factors. For every pair, you will pick only ONE number to represent the pair. Think of it like picking one person from each team of two for a final race!
144 = (2 x 2) x (2 x 2) x (3 x 3)
| | |
↓ ↓ ↓
2 2 3
Step 3: Multiply the numbers you picked from each pair.
2 x 2 x 3 = 12
Result: The square root of 144 is 12! And we know this is correct because 12 x 12 = 144. You've done it!
A Real-Life Story
Mzee Kamau, a wise farmer in Limuru, wanted to divide his large square piece of land for his grandchildren. The total area of the land was 400 square metres. He wanted to give each grandchild a small, perfectly square plot to grow their own vegetables. He first needed to know the length of one side of his entire land. He sat down and found the square root of 400. Using prime factorization, he found √400 = 20. So, his land was 20 metres by 20 metres. Now he could easily divide it!
Let's Practice! (K.C.P.E. Corner)
Here are some questions for you to try. Take your time, use the methods we learned.
- What is the value of 25²?
- A square meeting hall has an area of 225 square metres. What is the length of one of its walls?
- Find the square root of 784 using the prime factorization method.
...(Try them before you look at the answers!)...
Solutions
1. What is the value of 25²?
25² = 25 x 25
= 625
2. A square meeting hall has an area of 225 square metres. What is the length of one of its walls?
Area of a square = Length x Length. So, we need to find the square root of the area.
Length = √225
Let's use prime factors:
225 = 3 x 75
= 3 x 3 x 25
= 3 x 3 x 5 x 5
Pair them up: (3 x 3) x (5 x 5)
↓ ↓
3 5
Multiply the chosen factors: 3 x 5 = 15
The length of one wall is 15 metres.
3. Find the square root of 784.
√784
Prime Factors of 784:
784 = 2 x 392
= 2 x 2 x 196
= 2 x 2 x 2 x 98
= 2 x 2 x 2 x 2 x 49
= 2 x 2 x 2 x 2 x 7 x 7
Pair them up: (2x2) x (2x2) x (7x7)
↓ ↓ ↓
2 2 7
Multiply: 2 x 2 x 7 = 28
The square root of 784 is 28.
Key Takeaways
- A square number is a number multiplied by itself (e.g., 6² = 36).
- A square root is the number that was multiplied by itself to get the square number (e.g., √36 = 6).
- Prime Factorization is a powerful tool to find the square root of large numbers. Just break it down, pair them up, and multiply!
Excellent work today! You have learned a skill that is not only important for your exams but also for understanding the world around you. Keep practicing, and remember that just like building a house brick by brick, your knowledge in mathematics grows step by step. You've got this!
Pro Tip
Take your own short notes while going through the topics.