Compensation Divisibility
1. The problem asks us to describe compensation to add or subtract, give examples to teach Grade 4 learners, illustrate numbers with base 10 blocks, test divisibility, and use a place value chart.
2. Compensation means adjusting one number to make the calculation easier and then compensating by adjusting the other number.
3. Compensation to add example:
Example: Calculate $47 + 38$ by compensating.
Step 1: Adjust 38 to 40 (add 2 to 38).
Step 2: Add 47 + 40 = 87.
Step 3: Since we added 2 extra, subtract 2 from 87.
Step 4: Final answer is $87 - 2 = 85$.
Teaching tip: Show children that making numbers round helps addition, then fix the difference.
4. Compensation to subtract example:
Example: Calculate $63 - 27$ by compensating.
Step 1: Adjust 27 to 30 (add 3 to 27).
Step 2: Subtract 63 - 30 = 33.
Step 3: Since we added 3 to 27, add 3 back to 33.
Step 4: Final answer is $33 + 3 = 36$.
Teaching tip: Explain that adjusting the subtractor makes subtraction easier; then add back the adjustment.
5. Illustration using base 10 blocks:
5.1 For 101, show 1 hundred block, 0 ten blocks, 1 one block.
5.2 For 1436, show 1 thousand block, 4 hundred blocks, 3 ten blocks, 6 one blocks.
6. Test divisibility of 1,264,032:
- Divisible by 2: last digit is 2 (even), so divisible by 2.
- Divisible by 3: sum digits $1+2+6+4+0+3+2=18$; 18 divisible by 3, so divisible by 3.
- Divisible by 11: alternate sum difference $(1+6+0+2) - (2+4+3)=9-9=0$; 0 divisible by 11, so number divisible by 11.
7. Place value chart for 16,745:
Ten thousands: 1
Thousands: 6
Hundreds: 7
Tens: 4
Ones: 5
Final answers:
3.1 Compensation explained with examples in steps.
3.2 Base 10 blocks illustration for 101 and 1436.
3.3 Divisible by 2, 3, and 11: Yes to all.
3.4 Place value shown for 16,745.