does anyone have any links to websites for techniques for improving mental arithmetic speed - I used to be pretty sharp at it when I was like 15 but am a bit rusty now

general straight forward multiplication i.e. 274 *137

basically I want to get to the point where I can produce an answer in under 2 seconds for any 3 digit combinations

also something like

(2*108.33) - 114.73

or (3*108.33) - (2*114.73)

Whoa thats all kinds of too much hard work.


Im off to read Spot The Dog for a couple of hours to get back to normal!  



Seriously though fair play that stuff is something I just plain cant do.

Yeah whats with trying to introvert your sadist streak?

Quote from: Davegeneral straight forward multiplication i.e. 274 *137

basically I want to get to the point where I can produce an answer in under 2 seconds for any 3 digit combinations

I suggest Sapho juice


it is by will alone I set my mind in motion.......

Practice practice practice. Your brain is like most other organs, if you excersise it in a certain manner it will adapt to deal with that better.


I am the Qumkuat Haagen-Daas...

yeah was kind of looking for shortcuts/tricks

IIRC there was some japanese or chinese guy who taught kids to be super quick with an abacus - later hed take the abacus away and the kids would picture a mental abacus.

Basically he ended up with a classroom full of kids who could do say 482348*27549 in a couple of seconds.

Ive always worked out straight mathematical problems differently to most people. They will use the tried and trusted "1 plus 8, carry one, 2+9, carry two..." etc, whereas Ive always done this:

Say I need to know what 146 times 72 is.

Firstly, Id multiply 100 by 72 which = 7200.
Then, knowing I need to know what 46 x 72 is, Id do the easy thing and just multiply 50 x 72. Seeing as we already know that 100 x 72 = 7200 then 50 x must be 3600. But we have 4 x 72 too many dont we. So it equals 3600-288(3312).

So, we have 7200+3312=10512.

It sounds like a lot but once you get the hang of it and can keep several numbers in memory while you make the calculation, it gets easier.

So here is another example without all the yabbering:

216 * 450

216 * 400 = 84400

216 * 50 = (216 * 100) / 2) = 10800

84400 + 10800 = 95200.

Quote from: CheuleIve always worked out straight mathematical problems differently to most people. They will use the tried and trusted "1 plus 8, carry one, 2+9, carry two..." etc, whereas Ive always done this:

Say I need to know what 146 times 72 is.

Firstly, Id multiply 100 by 72 which = 7200.
Then, knowing I need to know what 46 x 72 is, Id do the easy thing and just multiply 50 x 72. Seeing as we already know that 100 x 72 = 7200 then 50 x must be 3600. But we have 4 x 72 too many dont we. So it equals 3600-288(3312).

So, we have 7200+3312=10512.

It sounds like a lot but once you get the hang of it and can keep several numbers in memory while you make the calculation, it gets easier.

I work the same way since Ive never been able to remember times tables. Instead I taught myself to figure them out starting from the easy ones (2 and 10). I never multiply anything by 5 for example, I find it quicker to halve it and multiply by 10. By the time I finished that stage of my schooling I was top of the class at tables tests, despite still not knowing any of them.

Ive never taken it as far as multiplying 3 digit numbers in my head though, to remember that many numbers at once I need a piece of paper.

Dr Kawashimas Brain Training?  

Quote from: Davedoes anyone have any links to websites for techniques for improving mental arithmetic speed - I used to be pretty sharp at it when I was like 15 but am a bit rusty now

general straight forward multiplication i.e. 274 *137

basically I want to get to the point where I can produce an answer in under 2 seconds for any 3 digit combinations

also something like

(2*108.33) - 114.73

or (3*108.33) - (2*114.73)

To be honest it would take me a few minutes (or more) to figure those out... Phone has a calc... that does me

i have severe problems with numbers, i have dyslexia in numbers as it were, there have been a few occasions where its quicker for me to ask someone "whats 35+7?" instead of working it out

Cheule - that is pretty much what I do at the moment

I guess I just need to practice & keep going over my times tables

(basically Ive got an interview where they are going to be firing off random mental maths questions at me - Ive got through the first two stages for this particular firm so dont want to blow it now because Ive got rusty at doing stuff that I used to be pretty quick with when I was 15)

I suppose its easier when you practice it as much as I do - some of my work includes auditing, we have pallets of stuff I have to quickly add up by looking at how many are on a layer (say 28) by the number of layers (say 9, which to me is 280-28=252). Often times I come across the same sorts of numbers to I can often skip some of the calculations as I remember the results already.

Dave - I hear you on the getting older bit. Unfortunately

EDIT: Oh, and good luck with the job mate!

Quote from: Daveyeah was kind of looking for shortcuts/tricks

IIRC there was some japanese or chinese guy who taught kids to be super quick with an abacus - later hed take the abacus away and the kids would picture a mental abacus.

Basically he ended up with a classroom full of kids who could do say 482348*27549 in a couple of seconds.

I had a book that claimed to offer that sort of training ... forgot where I put it  :whoops:

Dont u have to have the savant syndrome to be able to do that ?

yes breaking down into easy to count parts is a good method