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 blocks. For example, on a number line, moving to the right indicates addition, while moving to the left indicates subtraction. Understanding these concepts is crucial for solving more complex mathematical problems.

Let's consider the addition of 23 and 45. We can break it down as follows: First, add the tens: 20 + 40 = 60. Next, add the units: 3 + 5 = 8. Finally, combine these results: 60 + 8 = 68. Thus, 23 + 45 = 68. This step-by-step approach helps in ensuring accuracy.

For subtraction, let's look at 87 - 34. Start by subtracting the tens: 80 - 30 = 50. Then, subtract the units: 7 - 4 = 3. Combine these results: 50 + 3 = 53. Therefore, 87 - 34 = 53. Breaking down the problem into manageable parts can simplify the process.

Now, let's practice addition together. Solve the following: 56 + 27. Start by adding the tens: 50 + 20 = 70. Then add the units: 6 + 7 = 13. Combine these: 70 + 13 = 83. Discuss your thought process with a partner and ensure you understand each step.

Next, we will practice subtraction. Solve 92 - 48. Begin with the tens: 90 - 40 = 50. Now, subtract the units: 2 - 8. Since we cannot subtract 8 from 2, we need to borrow. This gives us 12 - 8 = 4. Combine the results: 50 + 4 = 44. Work with a partner to compare your methods.

Now it's your turn to practice independently. Solve the following problems: 34 + 29, 75 - 19, 48 + 36, and 100 - 57. Show all your working clearly. After completing the problems, review your answers with a classmate and discuss any mistakes you made.

• 77
• 78
• 79
• 80

Answer: 77

Adding 45 and 32 gives a total of 77.

• 35
• 36
• 37
• 38

Answer: 35

Subtracting 29 from 64 results in 35.

Answer: 105

Adding 58 and 47 gives a total of 105.

Answer: 45

Subtracting 45 from 90 results in 45.

• 41
• 42
• 43
• 44

Answer: 42

The sum of 23 and 19 is 42.

• 62
• 63
• 64
• 65

Answer: 63

Subtracting 37 from 100 gives 63.

Answer: 100

Adding 76 and 24 results in 100.

Answer: 56

Subtracting 29 from 85 results in 56.