Knaw's vignettes

A LiveJournal refugee posting short self-made videos on no particular theme, all in high definition and with transcripts where possible.

Willing to contribute to video projects.
Go on, ask something, I dare you
Posts tagged method

Lady Calc Calc.

After yesterday’s video about a method of multiplication using your fingers, I taught Lady Gav Gav. Here’s how she did.


"Hi, it’s Lady Gav Gav here. Gavin tried to show me a method yesterday of multiplying using only your hands, er with certain numbers of course. Erm, and I just thought I’d try and do this.

"So if you want to multiply, er, say, seven by eight, one of these is your seven finger and the other’s your eight finger. Think that’s it.

"Then you multiply the… no, you don’t multiply the bottom, you mult… no, you get… you count up… Do you know what? Sod this for a game of soldiers. [Taps at calculator.] Fifty-six.

"Carry on, you little blog hogs."

Finger food for thought.

Since recording this video, I’ve tried to teach Lady Gav Gav the method. Come back tomorrow 22/05/2012 at 7pm to find out how she got on.


"A fellow blogger and mathematician recently posted about a method of multiplying using your fingers, anything from from six times six to ten times ten.

"If you take those two fingers and they’re… they represent value six, seven, eight, nine and ten is your thumbs. So if you want to multiply, say, seven by eight, you’d connect the seven finger on one hand to the eight finger on the other.

"Now, I’ll take these away for the moment. You can see there’s two, four, five fingers below and including the joined ones. That’s your tens column, that’s fifty.

"And the rest of them. Three times two is six. Add them together, fifty-six. Try it with any other numbers from six to ten.

"This is great. I once bought a book on the Tractenberg system of speed mathematics with the intention of learning it. Now, I read it twice but I never quite mastered it. But this is so much easier.

"Carry on."

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