Mathemagic - Arthur Benjamin

[mooeypoo]

This is absolutely brilliant. I have a book at home that is filled with little mental tricks on how to do math quickly in your brain, including the "pneumonic" method; some of the tricks are laughably easy (but impressive to those who are unsuspecting) and some take a LOT of practice.

 

I am not even remotely close to anything even SIMILAR to what this guy does. It's absolutely amazing! I figured you guys would enjoy it too.

 

 

Since I know the book tricks in general (again, it's far from easy and I'm not really anywhere close to this level) I kinda looked for where he's stalling while he's calculating and where he uses humor to hide his mental tricks --- even so, this is insanely impressive.

[imatfaal]

pneumonic/mnemonic ? I think I need to watch the video to understand the difference - but my flash plugin keeps dying on SFN - could you post a link to the video as well? Or tell me how to get to the underlying link.

Edited March 25, 2011 by imatfaal

[mooeypoo]

Oops, I might have misspelled that word... Sorry. Mnemonic. Of course... meh.

 

Here's the link:

[Shadow]

I know this guy from The Teaching Company. He's really good.

[michel123456]

Mnemonics for mental calculation.

 

Arthur is impressive, but it has more to do with memory and less with calculation. The fact that Arthur finds the correct result by the beginning (from left to right, 3 billions, etc.) is an indication of mnemonics. Under standard calculation, the result begins by the end (from right to left, the solution for the last digit comes first).

 

I know only basic tricks for mental calculation, nothing from mnemonics. There is no comparison.

Edited March 26, 2011 by michel123456

[Cap'n Refsmmat]

Mnemonics for mental calculation.

 

Arthur is impressive, but it has more to do with memory and less with calculation. The fact that Arthur finds the correct result by the beginning (from left to right, 3 billions, etc.) is an indication of mnemonics. Under standard calculation, the result begins by the end (from right to left, the solution for the last digit comes first).

Having read Mr. Benjamin's book, I can say that he certainly does not use the standard calculations -- he uses mental methods that often result in getting the leftmost digit first. He does not memorize the computations in advance apart from basic things like single-digit squares.

[michel123456]

Does anyone here practice mental calculation?

[mississippichem]

This guy is amazing. He better stop, or Texas Instruments might have him killed.

 

[mooeypoo]

Does anyone here practice mental calculation?

A little bit, but after seeing that video, "a little bit" is a huge huge overstatement. I suck.

But I love knowing the tiny memory/math tricks that help with solving quickly, they help me later when I solve my own math equations on paper too.

 

~mooey

 

 

 

[michel123456]

A little bit, but after seeing that video, "a little bit" is a huge huge overstatement. I suck.

But I love knowing the tiny memory/math tricks that help with solving quickly, they help me later when I solve my own math equations on paper too.

 

~mooey

 

So do I.

For a reminder, the use of multiplication table is based on mnemonics. You calculate it once, then you put it in your memory and give back the result at any time without calculation. This is not what I call a calculation trick.

 

A calculation trick is for example to say that multiplication by 5 is the same as multiplication by 10 and division by 2. For example the result of 170*5 is 170/2=85 by ten gives 850. It is very useful for certain numbers:

242424242424242424*5=1212121212121212120

you can't do that on your pocket calculator.

[lamp]

Nice trick as well michel,

 

I'm reading Arthur Benamin's book as well, it's called Secrets of Mental Math if anybody is wondering. It is always funny how easy you can impress people with these tricks, I find this a good way to pick up girls by the way.

[michel123456]

There are others:

Dividing by 5 is the reverse (multiply by 2)

Multiplying by 25 is like dividing by 4, and reversely.

Divide by 125 looks difficult, but multiply by 8 is easy.

 

Also: multiplying by six is dividing by 2 changing the decimal (see precedent post) plus one time the value. For example 72*6= 360+72=432. it is not quicker than regular multiplying, but easier to do mentally.

 

You can do the same for multiplying by 3.

 

 

 

And a lot more I suppose. I am not so good at it.