Mathematics - Term 3 - Week 9

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 add 3 and 5, we can start at 3 on a number line and move 5 steps forward to land on 8. Conversely, if we subtract 5 from 8, we start at 8 and move 5 steps back to land on 3.

Let's solve the problem 27 + 45. We can break this down into smaller parts. 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.

Consider the problem 92 - 36. Start by subtracting the tens: 90 - 30 = 60. Then, subtract the units: 2 - 6. Since we can't subtract 6 from 2, we need to borrow 1 from the tens place, making it 12 - 6 = 6. Now, combine the results: 60 - 6 = 56. Thus, 92 - 36 = 56.

Now, let's work together on the problem 34 + 29. Start by adding the tens: 30 + 20 = 50. Next, add the units: 4 + 9 = 13. Combine these results: 50 + 13 = 63. So, 34 + 29 = 63. Can anyone explain how we can check our answer?

Let's try the subtraction problem 75 - 28 together. First, subtract the tens: 70 - 20 = 50. Now, subtract the units: 5 - 8. Since we can't do that, we borrow from the tens, making it 15 - 8 = 7. Combine the results: 50 - 7 = 47. Therefore, 75 - 28 = 47. Who can tell me how we can verify this result?

Now it's your turn! Solve the following problems on your own and show your working: 1) 56 + 37, 2) 84 - 29, 3) 45 + 68, 4) 100 - 47. Remember to break down the problems into manageable parts and check your answers by reversing the operations.

• 81
• 71
• 91
• 75

Answer: 81

When you add 45 and 36, you get 81.

• 45
• 55
• 65
• 75

Answer: 45

Subtracting 47 from 92 gives you 45.

Answer: I would subtract 27 from my answer, 85, to see if I get 58.

Checking by reversing the operation helps confirm the answer.

Answer: 34

Subtracting 29 from 63 results in 34.

• 72 + 19
• 72 - 10 - 9
• 72 - 20 + 1
• 72 - 19 + 0

Answer: 72 - 20 + 1

This breaks down the subtraction into manageable parts.

• 92
• 82
• 72
• 64

Answer: 92

Adding 34 and 58 results in 92.

Answer: 55

Subtracting 45 from 100 gives you 55.

Answer: 42

Adding 23 and 19 results in 42.