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The Magic Cafe Forum Index » » Magical equations » » Help needed with calculation (2 Likes) Printer Friendly Version

eSamuels
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Let me preface this by saying that I am mathematically challenged!
No word of a lie. I've spent over an hour trying to solve a problem that most people on this topic could probably do in a fraction of that time (pun somewhat intended!)

I'm trying to find a somewhat 'organic' way to force a 12-digit number using an add-a-no pad (I don't want to use toxic force).
The sum total target is 390121370641

Asking a few people to write down 11-digit numbers (and then having them added using a calculator) seems clunky, and I want the numbers to seem to have some personal relevance, so I thought I would do something like:

Person #1 "write down a telephone number from your childhood"
Person #2 "write down a street address (numbers only) from somewhere you used to live."
Person #3 "write down a PIN that you no longer use."

The pad is then handed to a 4th person who is instructed (using their phone calc) to multiply the first two numbers and then add (or subtract) the last number (or something to that effect).
When they do the calculations (without the need for any decimal points), the target 12-digit number is the result.

Yes, it's clunky, but I can't think of another clean way to get the the required result.
So, I am looking for help in figuring out either a formula to a specific calculation that will result in achieving the force number.

Appreciate any help - other than a suggestion that I take a remedial math course. Been there, done that. I failed that one too!

PS - I'm certainly open to any other forcing methods (other than an add-a-no pad) which might accomplish the desired result.

Cheers,

Eric
Thomas Henry
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Hello Eric,

That doesn't seem to be a very friendly number from a presentational standpoint. Because it's so large, forming products is the only reasonably quick way to get to its neighborhood, and even then the factors are going to be larger than most audiences will enjoy seeing manipulated. And that 390121370641 is a prime number makes it a little less amenable to any slick computation.

Most audiences won't be too keen on long-winded computations in any event, no matter how deceptive the method. Or such is my opinion.

Therefore, I'd suggest a fast approach that uses juxtaposition in lieu of computation. A gallon sized Ziploc bag is shown, filled with charitable raffle tickets, of three different colors (pink, light green and light blue), and each bearing a 4-digit lucky number. A participant grabs a handful and confirms they're all different and varied. These are returned to the bag and shaken.

Now three participants each reach in and remove a ticket, each taking a different color, which you explain helps randomize things.

A fourth participant, the secretary, then records the three numbers with a marker on a large tablet, abutting them side by side to form one large twelve-digit number. And it matches your prediction.

The method should be clear, which I'll avoid mentioning by name since this is a public forum. You can easily make the bag at home. Likewise the tickets are homemade as well, laser printed on pastel card stock. (Two decades ago I made up a ton of these myself for a different effect. I peppered them with images of dollar signs, shamrocks, dice showing "seven," etc., and put the usual contest rules stuff on the back.) The tickets you're interested in bear the numbers 3901, 2137, 0641. The others are a mix.

If you find the leading zero of the third number problematic, then you can use four 3-digit numbers instead, with four participants: 390, 121, 370, 641.

This would be much faster than any computational approach, since all the secretary has to do is juxtapose the numbers. And it avoids the tedium of computation, nor requires a calculator.

Anyway, just an idea...

Thomas Henry
Omne ignotum pro magnifico.
landmark
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So Eric, If I'm understanding you correctly, after the first three people write down their info, the add-a-no. pad is switched to another page with three of your pre-written numbers, yes? And you're asking which three numbers would work to result in an answer of 390121370641?

If that's the case, then here are a set of numbers that will work, but I switched the order of the PIN number and Address for more realistic looking numbers.

#1 Phone: 718-1778
#2 PIN 54321
#3 Address: 7903

Multiply the phone number by the PIN and then add the address to get your force number.
eSamuels
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Quote:
On Aug 29, 2019, Thomas Henry wrote:
Hello Eric,

That doesn't seem to be a very friendly number from a presentational standpoint. Because it's so large, forming products is the only reasonably quick way to get to its neighborhood, and even then the factors are going to be larger than most audiences will enjoy seeing manipulated. And that 390121370641 is a prime number makes it a little less amenable to any slick computation.

Most audiences won't be too keen on long-winded computations in any event, no matter how deceptive the method. Or such is my opinion.

Therefore, I'd suggest a fast approach that uses juxtaposition in lieu of computation. A gallon sized Ziploc bag is shown, filled with charitable raffle tickets, of three different colors (pink, light green and light blue), and each bearing a 4-digit lucky number. A participant grabs a handful and confirms they're all different and varied. These are returned to the bag and shaken.

Now three participants each reach in and remove a ticket, each taking a different color, which you explain helps randomize things.

A fourth participant, the secretary, then records the three numbers with a marker on a large tablet, abutting them side by side to form one large twelve-digit number. And it matches your prediction.

The method should be clear, which I'll avoid mentioning by name since this is a public forum. You can easily make the bag at home. Likewise the tickets are homemade as well, laser printed on pastel card stock. (Two decades ago I made up a ton of these myself for a different effect. I peppered them with images of dollar signs, shamrocks, dice showing "seven," etc., and put the usual contest rules stuff on the back.) The tickets you're interested in bear the numbers 3901, 2137, 0641. The others are a mix.

If you find the leading zero of the third number problematic, then you can use four 3-digit numbers instead, with four participants: 390, 121, 370, 641.

This would be much faster than any computational approach, since all the secretary has to do is juxtapose the numbers. And it avoids the tedium of computation, nor requires a calculator.

Anyway, just an idea...

Thomas Henry


Thanks for that, Thomas.

I actually make and market the specific forcing 'device' to which you are referring, but dismissed it (as well as several other of the forcing devices that I also manufacture and market), as they lack the specific 'personal' content that I'm seeking for this particular element.

But I appreciate your time and suggestion.

Cheers,

e
eSamuels
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Quote:
On Aug 29, 2019, landmark wrote:
So Eric, If I'm understanding you correctly, after the first three people write down their info, the add-a-no. pad is switched to another page with three of your pre-written numbers, yes? And you're asking which three numbers would work to result in an answer of 390121370641?

If that's the case, then here are a set of numbers that will work, but I switched the order of the PIN number and Address for more realistic looking numbers.

#1 Phone: 718-1778
#2 PIN 54321
#3 Address: 7903

Multiply the phone number by the PIN and then add the address to get your force number.


Well, you absolutely nailed it!

Please don't tell me that this took you all of 30-seconds to work out Smile
That aside, very much appreciated - Let me know if I can ever repay the favour!

Cheers,

e
landmark
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You know, I did think it was going to take 30 seconds to work out, and two hours later I wasn't laughing anymore. Finding reasonable looking numbers was more challenging than I thought it would be. Anyway, glad this works for you.

And Thomas Henry--How the heck did you know that 390121370641 was prime! Smile
eSamuels
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On Aug 30, 2019, landmark wrote:
You know, I did think it was going to take 30 seconds to work out, and two hours later I wasn't laughing anymore. Finding reasonable looking numbers was more challenging than I thought it would be. Anyway, glad this works for you.

And Thomas Henry--How the heck did you know that 390121370641 was prime! Smile



Not sure if your having spent 2-hours on this makes me feel better or worse!
But it's perfect, so thanks again!

e
Thomas Henry
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Hello Landmark,

Quote:
On Aug 30, 2019, landmark wrote:
And Thomas Henry--How the heck did you know that 390121370641 was prime! Smile


Thanks to the ever handy program wxMaxima:

https://wxmaxima-developers.github.io/wxmaxima/

This is open source, completely free of charge, and available for all computer types. I use it constantly to search for new principles in mathemagic, or to check various claims made which seem suspicious. There are tons of eBooks and tutorials for it out on the Web, too.

Thomas Henry
Omne ignotum pro magnifico.
Greg Arce
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Interesting take on it. I was going to suggest using the Eat At Joe's principle. You have a bunch of envelopes that you say contain various two digit numbers. Someone cuts into the stack and you deal out the first six envelopes from the stack. Now you go through the Eat At Joe's routine saying you want to further mix up the order of those numbers inside.

In the end they open up their envelopes, in a line, and it's your large 12 digit prediction.

Just a thought.

Greg
One of my favorite quotes: "A critic is a legless man who teaches running."
Greg Arce
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Oops, forgot to mention: The original stack of envelopes just has the six 2 digit numbers repeating, in that sequence, 3 times. So wherever they cut, the next six envelopes have your needed set. One is marked in all the sequences so you know to initially cut that small stack to the mark so it is is now in your needed sequence.
Greg
One of my favorite quotes: "A critic is a legless man who teaches running."
eSamuels
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Hey Greg,

'Eat At Joe's,' certainly achieves the required outcome but lacks the personal number source that I need for this specific presentation. I want each of the provided numbers to have personal history for the audience member.

But thanks for the suggestion.

e
landmark
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Quote:
On Aug 31, 2019, Thomas Henry wrote:
Hello Landmark,

Quote:
On Aug 30, 2019, landmark wrote:
And Thomas Henry--How the heck did you know that 390121370641 was prime! Smile


Thanks to the ever handy program wxMaxima:

https://wxmaxima-developers.github.io/wxmaxima/

This is open source, completely free of charge, and available for all computer types. I use it constantly to search for new principles in mathemagic, or to check various claims made which seem suspicious. There are tons of eBooks and tutorials for it out on the Web, too.

Thomas Henry


Ah, thanks.
Takwah
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This is not mathematical, but maybe you can generate a list of vanity numbers which you then may force to generate the impression that its related to the personal information of the spectator.

Another approach would be to force the vanity number from the personal information.

So what I am suggesting is, getting away from numbers to the letters of the alphabet and in the end convert it through the vanity system, which in combination with the inputs being personal information like a phone number would make total sense I think.

Take the digit root of the PIN for example this is calculated quickly and can be done in ones head, you get a number between 0 and 9. Have that relate to a chart with different vanity numbers which all translate to say the first x letters of the number you want to force.

In the end combine like three of four digit vanity numbers to form a sentence or word (where here the tricky part is, that all those combinations of 3x4 or 4x3 letter combinations have to be combinable in a useful way). If it wasn't required to be a prime number, you could go for it's prime factors, which should be equally sized. But that would change the forced number. So if you can find a number to your liking with equally sized prime factors.

Tak
saxonia
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Quote:
On Aug 31, 2019, Thomas Henry wrote:
Thanks to the ever handy program wxMaxima:

https://wxmaxima-developers.github.io/wxmaxima/

Thomas Henry


Alternatively, you can use https://www.wolframalpha.com for this kind or questions.

Ralf
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