Mathematics - Term 3 - Week 9

Addition is the process of combining two or more numbers to find their total, while subtraction involves taking one number away from another. To visualize these operations, we can use number lines, counters, or drawings. For example, if we have 5 apples and add 3 more, we can represent this on a number line starting at 5 and moving 3 steps to the right, landing on 8. Conversely, if we have 8 apples and take away 3, we move 3 steps to the left on the number line, landing on 5.

Let's solve the problem: 23 + 47. First, we can break down the numbers into tens and units: 20 + 40 = 60 and 3 + 7 = 10. Now, we add these results together: 60 + 10 = 70. Therefore, 23 + 47 = 70.

Consider the problem: 65 - 28. We can break this down as well: 65 can be viewed as 60 + 5. We subtract 20 from 60 to get 40, and then subtract 8 from 5, which gives us -3. Since we can't have negative units, we regroup: 40 - 1 (from the tens) gives us 39, and we add 10 to 5, making it 15. Thus, 65 - 28 = 37.

Now, let's practice addition together. Solve the problem: 34 + 29. Start by breaking it down: 30 + 20 = 50 and 4 + 9 = 13. Combine these results: 50 + 13 = 63. Write down your steps clearly. After you finish, share your method with a partner to compare strategies.

Next, let's tackle a subtraction problem: 82 - 37. Break it down into tens and units: 80 - 30 = 50 and 2 - 7 requires regrouping. So, we take 10 from the 50, making it 49, and add it to 2, giving us 12. Now, 12 - 7 = 5. Therefore, 82 - 37 = 45. Discuss your approach with your classmates.

Now it's your turn! Solve the following problems independently: 56 + 34, 91 - 46, 73 + 29, and 88 - 19. Show all your working clearly. Once you finish, check your answers with a partner and discuss any mistakes you made to understand the correct strategies.

• 81
• 71
• 91
• 75

Answer: 81

When you add 45 and 36, you get 81.

• 43
• 47
• 53
• 40

Answer: 43

Subtracting 57 from 100 gives you 43.

Answer: 102

Adding 78 and 24 results in 102.

Answer: 35

Subtracting 29 from 64 gives you 35.

• 77
• 68
• 79
• 76

Answer: 77

The sum of 29 and 48 is 77.

• 56
• 66
• 54
• 64

Answer: 56

Subtracting 34 from 90 results in 56.

Answer: 72

Adding 53 and 19 gives you 72.

Answer: 38

Subtracting 47 from 85 results in 38.