1. MathOnMonday® Presents: Building Math Courage®
A program designed for Adults or Kids who have struggled to learn their Math in the traditional classroom!
Lesson 20.9
Learning Your Nines
Dirk M. Horton

2. The Nines Pattern 9 + (10 – 1) = 18 + (10 – 1) = 27 + (10 – 1) = 36
Let’s count by nines by adding 9s using add 10 and subtract 1.
Click your mouse to see the pattern develop. 9
One Nine
+ (10 – 1) = 18
Two Nines
+ (10 – 1) = 27
Three Nines
+ (10 – 1) = 36
Four Nines
+ (10 – 1) = 45
Five Nines
+ (10 – 1) = 54
Six Nines
+ (10 – 1) = 63
Seven Nines
+ (10 – 1) = 72
Eight Nines
+ (10 – 1) = 81
Nine Nines
MathOnMonday© (March 2000)

3. 10’s Digit of Product
1’s Digit of Product
Multiply by
Click your mouse to find the relationship between the “multiply by” and the “10’s digit” of the product.
9 x 4 =
9 x 2 =
9 x 3 =
9 x 5 =
9 x 6 =
9 x 7 =
9 x 9 =
9 x 8 = 1 8
1 + 8 = 9
2 + 7 = 9
3 + 6 = 9
4 + 5 = 9
5 + 4 = 9
6 + 3 = 9
7 + 2 = 9
8 + 1 = 9 2 7 -1
The 10’s digit of the product
Is 1 less than the “multiply by”. 3 6 4 5
Click your mouse to find the relationship between the “10’s Digit” and the “1’s digit of the product. -1 5 4 6 3 -1 7 2
The 1’s Digit + the 10’s digit of the product always = 9. 8 1 -1
MathOnMonday© (March 2000)

4. Click your mouse to see that you learned your 9s
Click your mouse to see that you learned your 9s. Click for the problem, think about the 10’s digit, click again, and think about the 1’s digit, click again and see the result.
9 x 3 = 2 7
9 x 9 = 8 1
9 x 5 = 4 5
9 x 4 = 3 6
9 x 2 = 1 8
9 x 6 = 5 4
9 x 8 = 7 2
9 x 7 = 6 3
MathOnMonday© (March 2000)

5. Congratulations. You are learning your nines
Congratulations! You are learning your nines! Practice a few more times and you will be a nines expert!
9 x 3 = 2 7
9 x 9 = 8 1
9 x 5 = 4 5
9 x 4 = 3 6
9 x 2 = 1 8
9 x 6 = 5 4
9 x 8 = 7 2
9 x 7 = 6 3
MathOnMonday© (March 2000)