FRIHOST FORUMS SEARCH FAQ TOS BLOGS COMPETITIONS
You are invited to Log in or Register a free Frihost Account!


in interesting math problem





criticaldensity
of sorts...



1.Grab a calculator. (you won't be able to do this one in your head)
2. Key in the first three digits of your phone number (NOT the area code)
3. Multiply by 80
4. Add 1
5. Multiply by 250
6. Add the last 4 digits of your phone number
7. Add the last 4 digits of your phone number again.
8. Subtract 250
9. Divide number by 2

Do you recognize the answer?
sea
Laughing interesting... got back my own number... good one!
mOrpheuS
OK...to simplify the trick...
leaving out the remaining part, what we are doing essentially is adding 1 then multipying by 250 and then subtracting 250...that getting us back to square one. (x+1)*250 - 250=250x

and about the remaining part...
multiplying by 80 and then by 250...that's in effect, multiplying by 20000.
ie,
{first 3 digits * 20000 + 2*(last four digits)} / 2 =

first 3 digits * 10000 + last four digits = original number.

hmmm...
Wink
Bondings
mOrpheuS wrote:
OK...to simplify the trick...
leaving out the remaining part, what we are doing essentially is adding 1 then multipying by 250 and then subtracting 250...that getting us back to square one. (x+1)*250 - 250=250x

and about the remaining part...
multiplying by 80 and then by 250...that's in effect, multiplying by 20000.
ie,
{first 3 digits * 20000 + 2*(last four digits)} / 2 =

first 3 digits * 10000 + last four digits = original number.

hmmm...
Wink


And I thought he bewitched my calculator. Wink
It's really an interesting trick!
Conikair
Ooh, I love stuff like that! Very cool. Very Happy
irish_18
Its very cool! I like it! Wink
tommy.studio
Ya!
It is very cool!
I can use this to play my friends.
Firebolt
Its a very good trick but where do people get all these math things from there has got to be a site for all these things
dan751
Here's an interesting problem to this math problem...
I entered everything precisely as instructed, on my scientific calculator, I got "65703" only 5 digits, and on the calculator on the pc, I got "7423109". The scientific calculator is obviously no where near my home number. And I entered 742-3109 as my home number (I made it up). However, I only got it after the 4th time. The scientific calculator follows BEDMAS.
snowboardalliance
mOrpheuS wrote:
OK...to simplify the trick...
leaving out the remaining part, what we are doing essentially is adding 1 then multipying by 250 and then subtracting 250...that getting us back to square one. (x+1)*250 - 250=250x

and about the remaining part...
multiplying by 80 and then by 250...that's in effect, multiplying by 20000.
ie,
{first 3 digits * 20000 + 2*(last four digits)} / 2 =

first 3 digits * 10000 + last four digits = original number.

hmmm...
Wink


lol good job at solving that one. I was pretty sure it would show your number, just wasn't sure how exactly it did it.
myrevolt
yeah i tried it on my TI-89 Razz and had the same problem, but, see that's because the calculator is using the order of operations, where as the trick relies on it being in the specified order. remember PEMDAS (Parenthesises Exponents Multiplication, Division, Addition, Subtraction.) just do every step by step rather than all at once. cool trick, i am still trying to figure out the lil gimmick, gimme a sec.... Wink

UPDATE: Ok so all that add this, divide this gives you the equation: 10,000*x+y (where x is the first 3 digits and y is the last 4 digits)
completeforums
That's cool, I wonder who figured out that trick.
Thumpercats
That is a neat little trick. Nice job on figuring that one out! I will be sure to go and amaze some people with this trick. It is so simple, yet so interesting.
Arightwizard
Laughing This trick was amazing!..Until I read the other post..LOL Laughing
standready
Still a neat trick even after 3 years.
ftv_flung
Fantastic, I really like it hahaaaha

I'm gonna pass that one round Smile
Zuex
Lol, thats pretty good, i could work out someones number from just the first few numbers! Laughing
Afaceinthematrix
Zuex wrote:
Lol, thats pretty good, i could work out someones number from just the first few numbers! :lol:


You wouldn't need to. You're provided with the phone number already.



I've seen this problem before. It's extremely easy but it has so many steps that it essentially confuses and impresses many people.

2. Key in the first three digits of your phone number (NOT the area code)
3. Multiply by 80
4. Add 1
5. Multiply by 250
6. Add the last 4 digits of your phone number
7. Add the last 4 digits of your phone number again.
8. Subtract 250
9. Divide number by 2

Steps 4 and 8 pretty much cancel each other out. Steps 3 and 5 multiply to 20,000. Step 9 cancels out step 7 and outs the 20,000 to 10,000. So all you're doing is multiplying the first three numbers by 10,000 and then adding the last for so that you get the phone number. XXX turns into XXX0000 and then when you add YYYY you get XXXYYYY.
carlospro7
obviously this math trick can be broken down, and it's not a magic trick, but it's a pretty cool trick
jhamz
cool one......
blackfish
wow. that was pretty lame.
adri
Woow it actually works Surprised
vineeth
There are many others like this no? Its interesting but as you already gave your mobile number to the series, getting it back is not a big thing. The interest in this is because of the complex calculations involved.
linkmenot
mOrpheuS wrote:
OK...to simplify the trick...
leaving out the remaining part, what we are doing essentially is adding 1 then multipying by 250 and then subtracting 250...that getting us back to square one. (x+1)*250 - 250=250x

and about the remaining part...
multiplying by 80 and then by 250...that's in effect, multiplying by 20000.
ie,
{first 3 digits * 20000 + 2*(last four digits)} / 2 =

first 3 digits * 10000 + last four digits = original number.

hmmm...
Wink


exactly
Related topics
Joking....
A math problem only the smart can solve
Math problem!
Math Problem. 30 frih. (Solved!)
math problem with javascript
Solve this problem - 15frih$
Easy math problem- $20 frih
Someone feel like helping out with a math problem?
Math Problem
Maths problem
Solvr: Group Problem Solving Tool
A Math problem:Points in a 3D space (Quite hard)
New math problem a vector floating in space
Is there life beyond earth?
Reply to topic    Frihost Forum Index -> General -> General Chat

FRIHOST HOME | FAQ | TOS | ABOUT US | CONTACT US | SITE MAP
© 2005-2011 Frihost, forums powered by phpBB.