Mathematics - Term 4 - Week 7

Addition is the process of finding the total or sum by combining two or more numbers. Subtraction is the process of 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 by starting at 5 and moving 3 steps to the right to land on 8. Conversely, if we have 8 apples and we give away 3, we can start at 8 and move 3 steps to the left, landing on 5.

Let's solve the problem 27 + 15. We can break it down by adding the tens and the units separately. First, add the tens: 20 + 10 = 30. Next, add the units: 7 + 5 = 12. Now, combine these results: 30 + 12 = 42. Therefore, 27 + 15 = 42.

Now, let's look at the problem 54 - 29. We can also break this down. Start with the tens: 50 - 20 = 30. Then, subtract the units: 4 - 9. Since we can't take 9 from 4, we need to borrow 1 from the tens, making it 14 - 9 = 5. Now, combine the results: 30 + 5 = 25. Thus, 54 - 29 = 25.

Let's try the addition problem 34 + 28 together. First, add the tens: 30 + 20 = 50. Next, add the units: 4 + 8 = 12. Now, combine these results: 50 + 12 = 62. Write down the steps as we go along. Can anyone explain why we added the tens and units separately?

Now, let's work on the subtraction problem 76 - 34. Start with the tens: 70 - 30 = 40. Then, subtract the units: 6 - 4 = 2. Combine these results: 40 + 2 = 42. Who can tell me what we did when we subtracted the units?

Now it's your turn! Solve the following problems on your own: 1) 45 + 37, 2) 82 - 19, 3) 63 + 29, 4) 91 - 54. Remember to show your working clearly and check your answers. After you finish, pair up with a partner to review each other's work and discuss any mistakes.

• 92
• 82
• 72
• 94

Answer: 92

58 + 34 equals 92 when you add the tens and units together.

• 55
• 65
• 75
• 85

Answer: 55

100 - 45 equals 55 after subtracting the units and tens.

Answer: 46

Adding 27 and 19 gives you 46.

Answer: 36

Subtracting 28 from 64 results in 36.

• 92
• 102
• 82
• 112

Answer: 102

73 + 29 equals 102 when you add the numbers together.

• 53
• 63
• 73
• 83

Answer: 53

90 minus 37 equals 53.

Answer: 103

Adding 55 and 48 gives you 103.

Answer: 66

Subtracting 22 from 88 results in 66.