Lesson Notes By Weeks and Term v5 - Grade 3
Numbers 0–999: place value and operations (Grade 3) – Week 3 focus
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Numbers 0–999: place value and operations (Grade 3) – Week 3 focus
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Subject: Mathematics
Class: Grade 3
Term: 1st Term
Week: 3
Theme: General lesson support
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This week, we're continuing our journey into the world of numbers up to 999! Understanding numbers and how they work is super important. Think about it – when you go to the shop to buy sweets with your pocket money, you need to know how much things cost and how much change you should get back. When you're sharing toys or snacks with your friends, you need to count them accurately. Even telling the time involves understanding numbers! This week, we'll be focusing on understanding place value (hundreds, tens, and ones) and using this knowledge to solve simple addition and subtraction problems. This will help you become confident with numbers and use them in everyday situations.
Place Value: Hundreds, Tens, and Ones Every digit in a number has a specific place value. For numbers up to 999, we have three place values: Hundreds (H): This tells us how many groups of one hundred are in the number. The hundreds place is the third digit from the right.
Tens (T): This tells us how many groups of ten are in the number. The tens place is the second digit from the right.
Ones (O): This tells us how many individual ones are in the number. The ones place is the first digit from the right.
Example 1: Consider the number
2
8
5. The digit 2 is in the hundreds place, so it represents 2 hundreds, or
2
0
0. The digit 8 is in the tens place, so it represents 8 tens, or
8
0. The digit 5 is in the ones place, so it represents 5 ones, or
5. We can write 285 as 200 + 80 +
5. Decomposing Numbers Decomposing a number means breaking it down into its place value components. This helps us understand the value of each digit.
Example 2: Decompose the number 632. 632 = 600 + 30 + 2 6 is in the hundreds place (600) 3 is in the tens place (30) 2 is in the ones place (2) Addition with and without Regrouping When adding two numbers, we add the digits in each place value column, starting from the ones place. Sometimes, the sum of the digits in a column is greater than
9. When this happens, we need to regroup (carry over).
Example 3: Addition without Regrouping Add 324 + 152. ``` H T O 3 2 4 + 1 5 2 4 7 6 ``` Ones: 4 + 2 = 6 Tens: 2 + 5 = 7 Hundreds: 3 + 1 = 4 Therefore, 324 + 152 =
4
7
6. Example 4: Addition with Regrouping Add 257 + 165. ``` H T O 1 2 5 7 + 1 6 5 4 2 2 ``` Ones: 7 + 5 =
1
2. We write down 2 in the ones place and carry-over 1 to the tens place.
Tens: 1 (carried over) + 5 + 6 =
1
2. We write down 2 in the tens place and carry-over 1 to the hundreds place.
Hundreds: 1 (carried over) + 2 + 1 =
4. Therefore, 257 + 165 =
4
2
2. Subtraction with and without Borrowing When subtracting two numbers, we subtract the digits in each place value column, starting from the ones place. Sometimes, the digit on top is smaller than the digit below it. When this happens, we need to borrow from the next place value column.
Example 5: Subtraction without Borrowing Subtract 486 - 231. ``` H T O 4 8 6 2 3 1 2 5 5 ``` Ones: 6 - 1 = 5 Tens: 8 - 3 = 5 Hundreds: 4 - 2 = 2 Therefore, 486 - 231 =
2
5
5. Example 6: Subtraction with Borrowing Subtract 523 - 256. ``` H T O 4 11 13 5 2 3 2 5 6 2 6 7 ``` Ones: We can't subtract 6 from 3, so we borrow 1 ten from the tens place. This makes the ones place 13, and the tens place becomes 1. 13 - 6 =
7. Tens: We can't subtract 5 from 1, so we borrow 1 hundred from the hundreds place. This makes the tens place 11, and the hundreds place becomes 4. 11 - 5 =
6. Hundreds: 4 - 2 =
2. Therefore, 523 - 256 =
2
6
7. Guided Practice (With Solutions)
Question 1: What is the place value of the digit 7 in the number 372?
Solution: The digit 7 is in the tens place.
Therefore, its place value is 70 (7 tens).
Question 2: Decompose the number
4
1
9. Solution: 419 = 400 + 10 + 9 Question 3: Add 135 +
2
4
3. Solution: ``` H T O 1 3 5 + 2 4 3 3 7 8 ``` 135 + 243 = 378 Question 4: Add 268 + 154 Solution: ``` H T O 1 1 2 6 8 + 1 5 4 4 2 2 ``` 268 + 154 = 422 Question 5: Subtract 647 -
3
2
4. Solution: ``` H T O 6 4 7 3 2 4 3 2 3 ``` 647 - 324 = 323 Question 6: Subtract 421 -
1
7
5. Solution: ``` H T O 3 11 11 4 2 1 1 7 5 2 4 6 ``` 421 - 175 = 246 Independent Practice (Questions Only) What is the place value of the digit 5 in the number 851? Decompose the number
9
0
4. Write the number that is 3 hundreds, 6 tens, and 2 ones. Add 426 +
2
5
3. Add 375 +
2
4
8. Subtract 789 -
4
5
6. Subtract 532 -
2
8
7. Sipho has 235 marbles, and Thandi has 142 marbles. How many marbles do they have in total? Maria has 458 beads. She gives 123 beads to her friend. How many beads does Maria have left?
Which number is greater: 672 or 627? Explain your answer using place value.