Russian farmers are said to have used this method to multiply numbers between 6 and 10. The fingers are numbered from 6 to 10. Any couple can then be multiplied.
Emily shows off her nice nails:)
To multiply 7 & 8 you put the fingers representing the numbers against each other. The fingers that touch and those below represent tens. In this case 50. The other fingers are multiplied and then added to the numbers we got on the lower fingers. Three times two is six and added to the tens you get 6 + 50 = 56
Lucas and Rebecca examines whether the method works. It does! And it was fun!
in English: Are both hands labeled 6-10?
SvaraRaderayes
SvaraRaderaI don't get it. I'm not seeing how you get 50.
SvaraRaderaPlace fingertip 7 on first hand against fingertip 8 on the other hand. The touching fingers and those below (pointer and thumb on first hand and middle, pointer and thumb on the other hand) each represent 10. 5 fingers equals 50. The fingers above (middle, ring and pinky on first hand and ring and pinky on the other) represent 3 x 2= 6. 50 + 6=56
SvaraRaderaThis would take more time for my elementary student to figure out. Sorry but this is not helpful and your explanation is not very helpful.
SvaraRaderaHere's another example: 6x7...touch left thumb to right forefinger. You have 3 fingers total (two touching, one--the thumb--below). 3x10=30. Next, you have four fingers above your thumb on the left, and three above your forefinger on the right. that is 4x3=12. 30+12=42 (6x7=42).
SvaraRaderaI believe this is very helpful for those that like to think outside the box. I think The Egan 4's comment was rude. The explanation is fine. And the pictures help to show how to label the fingers. Thank you for showing us a new and different way to teach our students.
SvaraRaderaFascinating! Thanks for sharing!
SvaraRaderaVery interesting! Thank you for sharing the information. We are homeschoolers and the rote memorization of multiplication tables is monotonous. This will be fun to try.
SvaraRaderaPS your explanation was exquisite!
Quite interesting! Neat trick!
SvaraRaderaI also liked seeing how all multiples of 9 (1-10) sum up to equal 9, a nice trick to double check your answer:
9*2=18 (1+8=9)
9*3=27 (2+7=9)
9*4=36 (3+6=9)
9*12=108 (1+0+8=9)
9*27=243 (2+4+3=9)
works all the way up!
That is an awesome point! Thanks for bringing that to my attention. I am terrible at math (I am SOOO right brained) so any little tricks are a huge help to me.
RaderaLove this strategy...but can anyone explain why it works? That's where I'm stumped. :)
SvaraRaderaI've successfully taught this to fourth grade students for the past 5 years. There is a youtube video that is excruciatingly hard to watch because he goes so slow, but if you watch it a couple times it will be clear. http://www.youtube.com/watch?v=YL3PtlxYkZ4&feature=related
SvaraRaderaI have my kids write the numbers on their fingers with marker, but the sticky notes are a great alternative.
Multiples of nine is super easy. Hold out both hands with your fingers splayed. Let's say you're multiplying 9x3. Bend the middle finger of your left hand. You have 2 fingers (pinky and ring) to the left of your bent finger, and 7 to the right. 9x3=27. 9x7. Bend the pointer finger on your right hand. You have 6 fingers to the right of your bent finger, and 3 to the left. 9x7=63.
SvaraRaderathis is brilliant!!!
SvaraRaderaThis is a neat trick, but the blog post explains the very poorly. I had to read the comments to understand.
SvaraRaderaBrenda, thanks for explaining. I finally get it. The blog post was a little confusing.
SvaraRaderaI think there's a language barrier. The post introduces the method intriguingly, and I think the Egan 4's comment was unnecessarily harsh, but I will search for more information about this method elsewhere.
SvaraRaderaI'm going to have to Google it too. I don't get it. To be fair, I tend to struggle with math anyway...
SvaraRaderaI love your blog! I will try your Math trick with my 4th graders tomorrow. I will definitely be back to visit your blog. I would love to be able to write to your class from my class in California; we could set something up. =)
RaderaFabulous Finch Facts
I had to do it four or five times before I really "got it" but it was incredibly easy after that. Same for my 11 year old daughter.
SvaraRaderaI think a picture of the fingers touching would help the explanation. I am pretty good at math and it took me reading over and over and trying it several times to figure it out. I do get it, but a picture of the fingers touching would be a great help. Left finger touches right finger of the numbers you are multiplying. The fingers touching plus the fingers including thumbs are the 10s. Then the fingers above touching )towards pinkies are multiplied. Great idea!!!
SvaraRaderaThis is great! My daughters struggle with the higher numbers. We got it, thank you for sharing, I will use this in the classroom too. Multiple strategies :-)
SvaraRaderaThis is how my remedial math teacher taught us to do the higher numbers! I had forgotten how to do it!! Thanks!!
SvaraRaderaWow. Once I got the hang of it, I found it fascinating. I can't wait to share this.
SvaraRaderaBetter video than the previous given above. (from my point of view. At least quicker!)
SvaraRaderahttp://www.youtube.com/watch?v=twv-ynv_m9o
Lili