The Magic of the Number 9

Many of you may already be familiar with the magic of the number nine. For those of you who aren't, this may be helpful. And for those of you already familiar with the magic of the number nine, I have more to share that may be new to you.

The most common of the magic of nines, is the multiplying with your fingers. Lets do 9 X 3 = 27 to begin with. You take your third finger, because it is times 3. You fold that finger down. Now to the left of the third finger you have 2 fingers standing up. To the right of your third finger, you have seven fingers standing up. This is your answer. Twenty seven. This only works with nines, and it works with the nine table from 1 to 9.

The magic of nines also works for addition and subtraction. But this time, its not with your fingers.

Lets do this problem:

765
32
+109
906

The answer here, is 906, to check to see if it is right, we are going to add the digits cross ways. What do I mean? In your problem row one is 765, so we are going to add 7 + 6 + 5= 18 now we have to reduce all answers to one digit. So you then add the double digits together 1 + 8= 9. Now this is where we learn that the nines are magic. Every nine is valued as zero, nothing. We do this with each row, allow me to show you:

765 ~~~~~> 7 + 6 + 5 = 18 reduce it again 1 + 8 = 9 9 is equal to 0 (zero)
32 ~~~~~> 3 + 2 = 5 this number is reduced already.
+109 ~~~~~> 1 + 9 = 10 reduce it to one digit 1 + 0 = 1

Now you total your answers to the side. You have 5 and 1 and zero. Lets add these together, and we get ( 5 + 1 + 0 = 6) Your answer is 6. Now how does this help us to check? You proceed to do the same with your answer, you add the digits together. Our answer was 906. So lets add this, and we can do this one of two ways. 9 + 0 + 6 = 15 then reduce to 1 + 5 = 6. OR you can automatically pretend your nine is nothing, and SEE that your answer is 6, because without the nine, you have a zero and a six. If your digits match, from added down the side, and with your answer, your answer is right. BOTH answers in this case are 6, therefore your answer is right.

You can do this with subtraction too, and as you seen here in my example, addition. I learned this in seventh grade and have used it since. A Math teacher taught me, and every time I show people, including teachers, they are unfamiliar with this technique.

I hope you enjoyed learning the magic of nines with me today, and I hope you will share this with your friends and family!