🔢 Quick Study Guide
➕ - What are Compatible Numbers? 🤔Compatible numbers are numbers that are easy to compute mentally. They are close to the actual numbers but make multiplication simpler.
✖️ - Why Use Compatible Numbers? 💡 They help you estimate the answer to a multiplication problem quickly. This is useful when you don't need an exact answer.
📝 - How to Choose Compatible Numbers: Select numbers that are easy to multiply (e.g., multiples of 10, 100). For example, instead of 48 x 6, you might use 50 x 6.
🎯 - Estimating Products: Multiply the compatible numbers to find an estimated product. Remember, this is an approximation, not the exact answer.
📐 - Example: Estimating $32 \times 9$:
👍 - Round 32 to 30 (a compatible number).
✏️ - Multiply: $30 \times 9 = 270$.
✨ - So, the estimated product of $32 \times 9$ is 270.
Practice Quiz
1. Which of the following is the BEST compatible number to use for 28 when estimating 28 x 7?
A. 20
B. 25
C. 30
D. 35
2. Estimate the product of 19 x 5 using compatible numbers.
A. 50
B. 100
C. 150
D. 200
3. What compatible numbers could you use to estimate 41 x 8?
A. 40 x 10
B. 50 x 10
C. 40 x 8
D. 50 x 8
4. Estimate: 62 x 4 ≈ ?
A. 200
B. 240
C. 280
D. 300
5. Which expression uses compatible numbers to estimate 87 x 3?
A. 80 x 3
B. 90 x 3
C. 85 x 3
D. 95 x 3
6. Estimate the product of 34 x 6 using compatible numbers.
A. 120
B. 180
C. 210
D. 240
7. What is the estimated product of 56 x 9 using compatible numbers?
A. 450
B. 500
C. 540
D. 600
Click to see Answers
- C
- B
- C
- B
- B
- C
- C