Mathematics - Term 3 - Week 9

Addition is the process of combining two or more numbers to find a total, while subtraction is the process of taking one number away from another. To illustrate these concepts, we can use visual models such as number lines or base ten blocks. For example, if we have 5 apples and we add 3 more, we can visualize this on a number line by starting at 5 and moving 3 steps forward to reach 8. Conversely, if we have 8 apples and we take away 3, we can move 3 steps back on the number line to find that we have 5 apples left.

Let's solve the problem 27 + 45. We can break it down by adding the tens and the units separately. First, add the tens: 20 + 40 = 60. Next, add the units: 7 + 5 = 12. Now, combine these results: 60 + 12 = 72. Therefore, 27 + 45 = 72.

Now, let's look at the problem 82 - 29. We can also break this down. Start with the tens: 80 - 20 = 60. Then, subtract the units: 2 - 9. Since we can't subtract 9 from 2, we borrow 1 from the 60, making it 50, and now we have 12 - 9 = 3. Finally, combine the results: 50 + 3 = 53. Thus, 82 - 29 = 53.

Let's practice together. Solve 34 + 56. Start by adding the tens: 30 + 50. What do you get? Now, add the units: 4 + 6. Combine your answers. Who can share their solution? Remember to show your working clearly.

Now, let's try a subtraction problem: 65 - 28. First, subtract the tens: 60 - 20. What is that? Then, subtract the units: 5 - 8. If you can't do that, what do you need to do? Share your answers and show your working.

Now it's your turn! Solve the following problems on your own: 1) 48 + 37 2) 91 - 46 3) 76 + 19 4) 54 - 27. Remember to show all your working and check your answers. After you finish, pair up with a partner to discuss your solutions and any mistakes you might have made.

• 34
• 44
• 24
• 40

Answer: 44

15 + 29 = 44 when you add the tens and units together.

• 63
• 73
• 57
• 47

Answer: 63

100 - 37 = 63 after borrowing from the hundreds.

Answer: 82

58 + 24 = 82 by adding the tens and units.

Answer: 53

72 - 19 = 53 after borrowing.

• 71
• 81
• 91
• 61

Answer: 81

45 + 36 = 81 when you add the tens and units.

• 43
• 53
• 33
• 63

Answer: 43

88 - 45 = 43 after performing the subtraction.

Answer: 62

33 + 29 = 62 by adding the tens and units.

Answer: 28

50 - 22 = 28 after subtracting the units.