Unit 7 Contents

Is It Divisible by 9?

18. Copy and complete the list of facts for 9. Then write the products in a column, one on each line.
1 9 =
2 9 =
3 9 =
4 9 =
5 9 =
6 9 =
7 9 =
8 9 =
9 10 =


19. What patterns do you see? What can you say about the sum of the digits of the products?
20. Use your calculator to find more multiples of 9. Find the products below.
1. 9 634 =
2. 9 23 =
3. 9 37 =
4. 9 73 =
5. 9 143 =
6. 9 444 =
7. 9 754 =
8. 9 4421 =
21. Go back and add the digits of each product in Question 20.
    For example: 9 634 = 5706
    Add the digits in 5706: 5 + 7 + 0 + 6 = 18
    Now, add the digits in 18: 1 + 8 = 9
    Describe what happens when you add the digits of a multiple of 9.
1. Predict which numbers below are divisible by 9. Show how you decided.
2. Then check using a calculator.
3. Finally, write a multiplication and division sentence for each multiple of 9 you identify.

172	144	743	747	1007
2556	4906	8721	9908	12,987