A cool math trick

[sewchick]

There was a few more math tricks I used to know. My memory is not what it used to be. Slows with age.....I wasn't smart at anything growing up. Well sports if that counts. I had to work when I was young. It left me with little time for studies. I learned just the basics. I am smart with my hands if that counts. I am too old now to go back to school so my hands are my work. I envy anyone who is smart and has had the chance to get educated. It's such a wonderful thing to learn. It's a true gift. Now days one needs to be smart just to keep up with the technology. I only got a computer because of ebay and selling my stuff. That was 10 years ago. Now I have my own site and can even manage getting around the message boards pretty good. I am old school and can write the html without looking up anything. I think that is pretty good for an old fart.

Calculator....what is that?

I am still in the dark ages.

 

[Linda in San Diego]

I love teaching this to my sixth graders, particularly the ones that had trouble with math - and they demand to know why no one told them about it before. There are many little math tricks that help students who cannot memorize anything (other than song lyrics). But I love the ah-ha moment for the ones that have always struggled with the nines - and I tell them it was taught to me by students and helped me - I am one that could not memorize them either until I learned some "tricks".

 

[sewchick]

Quote:
I had a special math teacher that had us play cribbage. I have never forgotten her. Her name was Mrs. Burns. It was a good way to learn combinations. Boy that was a long time ago. She was my favorite teacher. I would probably not know how to do math as good as I do if it wasn't for her. What a nice memory.

 

[Linda in San Diego]

Quote:
I had a special math teacher that had us play cribbage. I have never forgotten her. Her name was Mrs. Burns. It was a good way to learn combinations. Boy that was a long time ago. She was my favorite teacher. I would probably not know how to do math as good as I do if it wasn't for her. What a nice memory.

My special math teacher was Mrs. Warwick - I was sure I was no good at math, she paired me up with a student that knew less than I did and we did our math homework together over the phone most evenings. I really had to understand what I was doing to help the other student - over the phone without visual aids was a challenge sometimes. But it was my first time teaching someone else - guess it stuck.

I love remembering my good teachers and hope I am some that for some of mine.

 

[sewchick]

Quote:
I think kids remember the little things that make a teacher special. I am sure your students will think that of you and probably already do.

I would like to teach some young people my skills. If it is not kept alive it will die with lack of interest over the years. A few things have already. Tatting is a thing of the past. I don't know anyone who can tat (making lace). I can't. I want to learn it. I have tried here online without success. Braided rugs that's another thing that is not done so much anymore. Not around here anyways.

 

[Linda in San Diego]

At the San Diego County Fair we always have folks tatting - fun to watch.
As for a braided rug. I helped my grandmother make her braided rugs. It started with buying wool clothing at this huge fabric market in LA. I also helped her as she actually made the rug to custom fit her living room, I was allowed to stitch the braids together with her watching. When she sold the house, she sold the rugs also - they would not have fit into any other room in the world.

 

[Linda in San Diego]

If you read the trick and did not get it, here is an explanation that might help, along with a couple of other tricks for the 9s.

9x1= 9 We all get that one for free. All the ones after that the fellow just counted backwards from 9
9x2= 8
9x3 =7
9x5 =6 and so on down the line

Then the counting starts over from the bottom and that number is placed in front of the number that is there.

9x1 = 9
9x2 = 18
9x3 = 27
9x4 = 36
9x5 = 45
9x6 = 54
9x7 = 63
9x8 = 72
9x9 = 81

I then teach my students that the first digit in the answer goes up while the second digit goes down. We also take time to notice that all the answers for 9 add up to 9 so if you brain tells you the answer to a 9s problem is 56, it simply cannot be - 5+6 does not add up to 9.

Third trick for 9s works this way
Teacher asks "What is 9x7?" You think, one less than 7 is 6, I need 3 more to make 9, you then answer the teacher in a firm voice - "9x7 is 63." She can't believe you suddenly know your 9s! She asks you another one, "What is 9x5?" You think for a moment, one less that 5 is 4, how much more do I need to make 9? and you answer once again, "9x5 is 45!" You now advance to smartest math student in the class!
The answer is always one less than the number being multiplied by 9 and then what ever is needed to make the answer add to 9.

 

[sewchick]

Quote:
Braided rugs are so beautiful. I have a couple of small ones that I love. There's a few tatting sites online. I am not a member because I really don't get it. I have seen a woman tatting at our fairs. That's about it though. No one in our family did tatting. Mostly crochet.

I still didn't get the post above. I can get the nine table but I am lost at what you are trying to say . I will get my dh to study it. He's a true bookworm. He should have taught school. He has a few degrees in something. I don't remember. Some science thing. Dunno.