Excerpt from Essentials of Homeschool: How to successfully teach your children at home ©Copyright 2020
Having a tough time with multiplication tables? Try this finger trick to learn how to multiply by 9. I never heard of this until I was an adult. I wish I’d learned it as a child! Here’s the rundown:
Hold both hands in front of you, palms down, fingers spread apart. Pick a number 1 through 10 that you want to multiply by 9. Then count that many fingers, always starting with your left pinky and moving toward your right pinky. When you get to the number you picked, stop and bend that finger, keeping all the other fingers straight.
Let’s pick the number 6. To solve 9x6, start counting from your left pinky.
1 = left pinky
2 = left ring finger
3 = left middle finger
4 = left pointer finger
5 = left thumb
6 = right thumb
In our example, your sixth finger is your right thumb. So bend your right thumb under.
The total number of fingers to the left of the bent finger give you the first digit of your answer. In our example there are five fingers to the left of the right-hand thumb, so the first digit of our answer is 5.
The total number of fingers to the right of the bent finger give you the second digit of your answer, or in our case, 4.
So 9x6 is 54.
Remember, never count the bent finger. Whichever finger you bend becomes the neutral wall between the answer’s two digits.
Try it again with the number 4. What’s 9x4? Start counting from your left pinky.
1 = left pinky
2 = left ring finger
3 = left middle finger
4 = left pointer finger
Your left pointer finger is the fourth finger, so bend it under.
You’ll notice three fingers are on the left side of the bent finger, so the first digit of your answer is 3.
Six fingers are on the right of your bent finger (your left-hand thumb plus all five of your right-hand fingers). So the second digit of your answer is 6. Put the two digits together and you get 36, the correct answer. 9x4=36. Amazing, eh?
When I introduced this trick to my daughter, she didn’t quite catch it at first. To help her out, I drew two horizontal lines on a piece of paper, with a vertical red line, or “wall,” between them. This is where she would write her answer. I taped a small, red piece of paper on top of whichever finger she bent to correspond with the red line on the paper in front of her.
When I asked how many fingers were to the left of her red “wall,” she had to write the number down on the left side of the red line. We repeated with the right side and voila! She’d written the answer. The visuals helped her grasp the concept and it didn’t take long to master her nine times table.