Mathematics - Term 4 - Week 7

Addition is the process of finding the total or sum by combining two or more numbers. Subtraction, on the other hand, involves finding the difference between numbers by 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 we add 3 more, we can represent this on a number line starting at 5 and moving 3 steps to the right to reach 8. Conversely, if we have 8 apples and give away 3, we can start at 8 and move 3 steps to the left, landing at 5.

Let's solve the addition 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, consider the subtraction problem 85 - 29. We can also break this down. Start by subtracting the tens: 80 - 20 = 60. Then, subtract the units: 5 - 9. Since we cannot subtract 9 from 5, we need to borrow 1 from the tens, making it 15 - 9 = 6. Now, combine the results: 60 - 6 = 56. Thus, 85 - 29 = 56.

Let's practice together with the problem 34 + 28. Start by adding the tens: 30 + 20 = 50. Next, add the units: 4 + 8 = 12. Combine these results: 50 + 12 = 62. Now, try another one: 56 + 37. Work through the steps and share your answers with a partner.

Now, let's work on a subtraction problem: 72 - 34. First, subtract the tens: 70 - 30 = 40. Then, subtract the units: 2 - 4. Since we cannot do this, we need to borrow from the tens, making it 12 - 4 = 8. Combine the results: 40 - 8 = 32. Try solving 91 - 46 and discuss your approach with a classmate.

Now it's your turn to practice on your own. Solve the following problems: 48 + 36, 63 - 29, 75 + 18, and 92 - 54. Show all your working steps clearly. Once you finish, exchange your work with a partner to check for accuracy and discuss any mistakes.

• 62
• 72
• 52
• 82

Answer: 72

Adding 45 and 27 gives a total of 72.

• 63
• 73
• 83
• 93

Answer: 63

Subtracting 37 from 100 results in 63.

Answer: 92

Adding 58 and 34 gives a total of 92.

Answer: 47

Subtracting 29 from 76 results in 47.

• 42
• 32
• 52
• 22

Answer: 42

Adding 23 and 19 gives a total of 42.

• 44
• 54
• 34
• 64

Answer: 44

Subtracting 45 from 89 results in 44.

Answer: 95

Adding 67 and 28 gives a total of 95.

Answer: 28

Subtracting 22 from 50 results in 28.