Just a question, how do you calculate quickly in your head...such as large numbers to multiply etc etc, sq roots etc etc. Pencil and paper is too slow, is there a faster way that you can learn?

I've looked in the internet and only found books (which cost CASH), anybody know any links, or method names, etc etc?

I'm just curious, maybe sum1 else may be interested. >_>

Oh, is there something with the hand finger techinique...something like that?

well for me. if it's something like 27x82
i'd do 20x80 then add the 14 from 7x2
idk i do it like that for sum reason :-\

I'm confused .. do you nott noah the means of calculating the cost of the math books?

lol only keith would say somethin like that :P

Nonono...like have u ever seen people who can do arithmatic really fast, like 84028483x283343 in less than 5 seconds no pencil or paper.

So far i've seen
1) The imaginary abacus <-- which takes years of practice, good memory, and part geniousness
2) My dad was referring to this thing were u use your fingers in some funky fashion to come up to you final answer (no it's not counting your fingers). <-- may also require years of practice, good memory, and part geniousness, but i would like to at least try
3) Anybody know a 3 is basically my question? Or the name of 2)?

andy griffith is on, and dinner is ready, cya.

btw when i get 27x82 i resort to the Ti-84 plus (not silver edition), ocasionally the Ti-30 ..or is it the 35..hmm...

i never use the slide rule. =P

I hope you are not looking for this "trick".

I am in a scientific field and I rarely have to do precise math like you are describing, so I'm not sure why you are looking to do this in the first place. My thinking is that if it needs to be precise then you can afford to get and use a calculator. For quick approximations I usually just factorize one or both of the numbers and then calculate the answer by grouping the numbers in a way that is easier for my brain to process them. For example: 123x45=123x(5x3x3)=((123x5)x3)x3=(((123x10)/2)x3)x3

I think it's more of a techinique, but I'm not sure if you have to be mentally retarded (same thing as genius >_> )...just wondering.

Why do I want to know? No particular use, just the fact that there has to be a better way that i could learn (aka, nothing better to do).

As for your factoring way, that sounds like a pretty good "technique", i should try it. (though i think thats how most every1 does it).

*caedes was the one who calculated how far the mars probe had to go before turning left

;o)

Gah, I hope not. =P

Btw, I think having a good short-term memory, and being, uh, what was the word, autistic savant, is the only way.

So, that leaves me with the abacus...hmmmm, hmmm hmmm..........I'll think about this one for a bit.

Well, i can add, subtract, and multiply with an abacus so far...now i need to practice that in my head for a while, then i'll move on the division and exponents. :S (can it do that?) =P

*this is so much fun* (By now u should be scared)

...after trying this, the abacus method is...possible to do quickly in your head....with practice...with multiplication and addition and subtraction so far...

...now practicing more, you have to have a good short term memory, but i still think it may be possible... (just htought u might be interested)

I don't even know the times table by heart anymore...I use Chismbop to do all multiplication of single digits...if a calculator isn't handy. If it's double digits or more a calculator is required or the work will have to wait.

8~D

Whatsa square root?

Speaking of which, math class today I spaced out...but thats a different story.

Whatsa chismbop? =P

(The abacus method is hard/impossible. My memory cant last long enough)

...also known as Chisnbop

The hands are held in a relaxed posture on or above a table. All fingers are floating off the table to begin with. The fingers are pressed into the table to indicate value.

Each finger (but not the thumb) of the right hand has a value of one. Press the index finger of the right hand onto the table to indicate "one." Press the index and long fingers for two, the three leftmost fingers for three, and all four fingers of the right hand to indicate four.

The thumb of the right hand holds the value five, like the top bead of a soroban or abacus. To place the value 6, press the right thumb and index finger onto the table. The thumb indicates 5 plus the 1 indicated by the finger.

The left hand represents the tens digit. It works like the right hand, but each value is multiplied by ten. Each finger on the left hand represents ten, and the left thumb represents fifty. In this way, all values between 0 and 99 can be indicated on two hands.

pretty nifty, so basically its like an abacus with just 2 columns...

that means you cant multiply stuff like: 25x25 ..so it kindof defeats the purpose...

Thanks for the info, it was rather helpful. >_>

I'm hear to teech, its whut I do's bestest!!

8~P

As long as you dont teech literature. ;-)

I have someone else do it.

That works good...unless your the smarter person.

*cough cough* "you're" need i say more? 8•P

i do that all the time! Their, there, they are...your flowers you're flowers...your the msarter person you're the smarter person...grrrr....

Who's smarter...the one doing it...or the one who can get someone else to do it?

Well if YOU'RE (I spelt it right this time, i think) the smarter person, than that means it would be a smart choice for you to do it..however if your the dumber of the two, let the smarter person do it...

...why copy sum1 who isnt as smart as yourself? =P

That's just it my anal attentive little friend the smarter person will have someone else do it. If you are the dumber of the two you will be doing the work.

"fools and mules work hard" see, somoene even came up with an expression about it.

Are you saying YOU ARE (i got it right again! Weee!..no more yours) a fool Rob (b/c your work, right?)...thats your name right? Let me check...wow, it really is Rob (I'm not so good with names)...

Guys...can SOMEONE, ANYONE explain to me in English what the hll Caedes said???!!! Just reading his entry gave me a headache.

Quite simple...

1) factor the numbers so they are smaller
2) Then multiply the easy numbers together
3) Done

He used 123 x 45 for ex:

1) Factor to a reasonable extent: 123 x 45 = 123 x 5 x 3 x 3
2) Multiply the numbers that would make the most sense to multiply and add a 2 to make things easy: 123 x 5(2) = (123 x 10)/2 = 1230/2 = uhhh...615?

615 x 3 x 3...easier to do 615 x 6 IMHO so: 615 x 6 = 3690 if my mental math is correct.

Improvise is the key.

Again, I say...HUH???

Factor, think, solve in short.

yeah...I was an english major for a reason

well thats good, then you should know the noahnott dialect. at least you somewhat understand my language. ;øP

I'm glad you guys cleared this up so I don't have to explain it. I could make King Kaedes sound like Bubba down at the Tex-Mex Bar and Grill.