Whole numbers, common fractions and decimals (Grade 6) – Week 1 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Subject: Mathematics
Class: Grade 6
Term: 1st Term
Week: 1
Theme: General lesson support
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
Welcome, Grade 6 learners! This week, we're diving into the fascinating world of whole numbers, common fractions, and decimals. These aren't just abstract concepts; they're the building blocks for understanding the world around you, from sharing a pizza with your friends to calculating discounts at the shops or even understanding cricket scores. They are crucial for managing pocket money, understanding recipe proportions, and even planning a trip. A solid understanding of these concepts will set you up for success in later math topics and everyday life.
Whole Numbers: Place Value and Operations Whole numbers are the counting numbers (0, 1, 2, 3, and so on). Understanding place value is vital when working with larger numbers. Each digit in a number has a specific value depending on its position. For example, in the number 567 321: 1 is in the ones place (value: 1) 2 is in the tens place (value: 20) 3 is in the hundreds place (value: 300) 7 is in the thousands place (value: 7 000) 6 is in the ten thousands place (value: 60 000) 5 is in the hundred thousands place (value: 500 000) Therefore, 567 321 is read as "Five hundred and sixty-seven thousand, three hundred and twenty-one." Ordering Whole Numbers: To order numbers, compare the digits from left to right, starting with the largest place value.
Example 1: Ordering Whole Numbers Order the following numbers from smallest to largest (ascending order): 123 456, 98 765, 123 400, 98 700 Compare the hundred thousands place: 123 456 and 123 400 both have "1", while 98 765 and 98 700 have "0" (they're smaller).
Compare 123 456 and 123 400: They are the same up to the hundreds place. Compare the tens place, 50 is greater than
0
0. So, 123 400 is less than 123
4
5
6. Compare 98 765 and 98 700: They are the same up to the hundreds place. Compare the tens place, 60 is greater than
0
0. So, 98 700 is less than 98
7
6
5. The order is: 98 700, 98 765, 123 400, 123 456 Addition and Subtraction of Whole Numbers: Ensure you align the numbers according to their place value before adding or subtracting. Remember to carry over or borrow when necessary.
Example 2: Addition of Whole Numbers Calculate: 234 567 + 189 765 ``` 234 567 + 189 765 424 332 ``` 7 + 5 = 12 (write down 2, carry over 1) 6 + 6 + 1 = 13 (write down 3, carry over 1) 5 + 7 + 1 = 13 (write down 3, carry over 1) 4 + 9 + 1 = 14 (write down 4, carry over 1) 3 + 8 + 1 = 12 (write down 2, carry over 1) 2 + 1 + 1 = 4 Example 3: Subtraction of Whole Numbers Calculate: 567 890 - 345 678 ``` 567 890 345 678 222 212 ``` 0 - 8 (We need to borrow. Borrow 1 from the 9, making it 8, and add 10 to the 0, making it
1
0. So, 10 - 8 = 2) 8 - 7 = 1 8 - 6 = 2 7 - 5 = 2 6 - 4 = 2 5 - 3 = 2 Common Fractions: Parts of a Whole A common fraction represents a part of a whole. It has a numerator (the top number) and a denominator (the bottom number). The denominator tells you how many equal parts the whole is divided into, and the numerator tells you how many of those parts you have. For instance, 1/4 means one part out of four equal parts.
Example 4: Imagine a pizza cut into 8 equal slices. You eat 3 slices. You ate 3/8 of the pizza.
Comparing and Ordering Common Fractions: When comparing fractions with the same denominator, the fraction with the larger numerator is greater. When comparing fractions with different denominators, you need to find a common denominator. The easiest way to do this is to find the Lowest Common Multiple (LCM) of the denominators.
Example 5: Comparing fractions with different denominators Compare 1/2 and 2/
5. Find the LCM of 2 and
5. The LCM is
1
0. Convert both fractions to have a denominator of 10. 1/2 = (1 x 5) / (2 x 5) = 5/10 2/5 = (2 x 2) / (5 x 2) = 4/10 Now compare: 5/10 > 4/
1
0. Therefore, 1/2 > 2/
5. Decimal Fractions: Another Way to Represent Parts of a Whole Decimal fractions are another way to represent parts of a whole, using a decimal point. The digits to the right of the decimal point represent fractions with denominators that are powers of 10 (10, 100, 1000, etc.). 0.1 = 1/10 (one-tenth) 0.01 = 1/100 (one-hundredth) 0.25 = 25/100 (twenty-five hundredths)
South African Currency: Rands and cents are an excellent example. R1.50 means 1 Rand and 50 cents, which is 1 and 50/100 Rands.
Adding and Subtracting Decimal Fractions: Just like with whole numbers, align the decimal points before adding or subtracting.
Example 6: Adding Decimals Calculate 1.25 + 0.75 ``` 1.25 + 0.75 2.00 ``` Example 7: Subtracting Decimals Calculate 3.50 - 1.25 ``` 3.50 1.25 2.25 ``` Guided Practice (With Solutions)
Question 1: Order the following numbers from largest to smallest: 456 789, 456 798, 456 700, 456 000 Solution: The hundred thousands, ten thousands, and thousands digits are all the same (456). We need to look at the hundreds digit. 798 has 7 in the hundreds place and 789 also has 7 in the hundreds place, 700 also has 7, whereas 456 000 has 0 in the hundreds place. Comparing 798 and 789, the tens place determine the order.
Therefore, 456 798, 456 789, 456 700, 456
0
0
0. Question 2: A farmer has 1/3 of his land planted with maize and 1/4 planted with sunflowers. Which crop covers more land?
Solution: We need to compare 1/3 and 1/
4. The LCM of 3 and 4 is 12. 1/3 = (1 x 4) / (3 x 4) = 4/12 1/4 = (1 x 3) / (4 x 3) = 3/12 Since 4/12 > 3/12, maize covers more land.
Question 3: Sipho buys a packet of chips for R5.50 and a juice for R3.
2
5. How much does he spend in total?
Solution: We need to add R5.50 and R3.25. ``` R5.50 +R3.25 R8.75 ``` Sipho spends R8.75 in total.