Fun with Mathematics
- UncleJoseph
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Fun with Mathematics
Ok, a friend emailed this to me. I get these things all the time.
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?
Somebody tell me how these damn things work. I know it's probably simple, like "multiplying any number by two and then dividing that number by two will give you the number you started with," but these formulas always seem more complicated than that, and I've had Calculus 101 and 102.
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?
Somebody tell me how these damn things work. I know it's probably simple, like "multiplying any number by two and then dividing that number by two will give you the number you started with," but these formulas always seem more complicated than that, and I've had Calculus 101 and 102.
If you take away their comforts, people are just like any other animal.
- Anguirel
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Re: Fun with Mathematics
Ok, let's do this... Step 4 and step 8 cancel out. Adding 1 prior to multiplying by 250 is the same as adding 250 after and then subtracting it. So that's a total cancellation.UncleJoseph wrote: 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
80*250 is 20,000, divided by 2 is 10,000 -- this moves the first three numbers you typed in over 4 places. Adding in twice the remaining four digits, then dividing by two leaves you with just those digits in the thousands column through the singles column.
I haven't done it, but I'd imagine you end up with your phone number. Does that explain it well enough?
complete. dirty. whore.
_Patience said: Ang, you are truly a font of varied and useful information.
IRC Fun:
<Reika> What a glorious way to die.
<Jackal> What are you, Klingon?
<Reika> Worse, a paladin.
<Jackal> We're all fucked.
_Patience said: Ang, you are truly a font of varied and useful information.
IRC Fun:
<Reika> What a glorious way to die.
<Jackal> What are you, Klingon?
<Reika> Worse, a paladin.
<Jackal> We're all fucked.
- UncleJoseph
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I tried it several time, double checked my numbers and its still doesn't match.
It work with my mother's phone number but not with mine.
It work with my mother's phone number but not with mine.
Last edited by Ikarus7 on Wed Feb 25, 2004 1:45 am, edited 1 time in total.
<hr>The lesson here is that dreams inevitably lead to hideous implosions.
- UncleJoseph
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I think I figured out why it's working for some and not others. With most calculators of today, you can key in several operations before pressing "=" or the calculate key. If you do this, the calculator will obey all rules of arithmetic, and will carry out multiplication and division before doing any addition or subraction.
If you press the "=" or calculate button after every step, the formula should work fine.
Eg: Test phone number 123-4567
123 x 80 = 9840
9840 + 1 = 9841
9841 x 250 = 2,460,250
2,460,250 + 4567 = 2,464,817
2,464,817 + 4567 = 2,469,384
2,469,384 - 250 = 2,469,134
2,469,134 / 2 = 1234567 -- our test phone number
If you wait until the entire formula is entered before pressing "=" or calculate (example above yields 19,099,) the answer will be slightly off, or way off, depending on when and how many times you used the "=" or calculate buttons.
If you press the "=" or calculate button after every step, the formula should work fine.
Eg: Test phone number 123-4567
123 x 80 = 9840
9840 + 1 = 9841
9841 x 250 = 2,460,250
2,460,250 + 4567 = 2,464,817
2,464,817 + 4567 = 2,469,384
2,469,384 - 250 = 2,469,134
2,469,134 / 2 = 1234567 -- our test phone number
If you wait until the entire formula is entered before pressing "=" or calculate (example above yields 19,099,) the answer will be slightly off, or way off, depending on when and how many times you used the "=" or calculate buttons.
If you take away their comforts, people are just like any other animal.
- UncleJoseph
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Ik,
It's a sound formula. It should work for any seven digit phone number. I tried it with 32's number and got his phone number at the end. I don't know where the error would be. The first time I tried it, I used the Windows calculator, and it worked fine. Haven't a clue why it doesn't work for you.
It's a sound formula. It should work for any seven digit phone number. I tried it with 32's number and got his phone number at the end. I don't know where the error would be. The first time I tried it, I used the Windows calculator, and it worked fine. Haven't a clue why it doesn't work for you.
If you take away their comforts, people are just like any other animal.
It's not really too complicated. Split your phone number: XXX | YYYY
XXX * 80 * 250 (Steps 3 and 5) = XXX * 20,000 = 2 * XXX * 10^4
It doubles the first three numbers, and adds four zeroes to the end of it. Step 4 is currently irrelevant, because +1 before multiplying is merely the addition of another 250 (Step 5), which only affects the digits in the last four spaces which we've added to hold the last four digits.
So now we have 2 * XXX | 0000 + 250 (Step 4). The last four steps are simply adding the YYYY twice ( = 2*XXX | 2*YYYY + 250), getting rid of the 250, and halving the whole thing ( = XXX | YYYY)
And that is why math is boring.
XXX * 80 * 250 (Steps 3 and 5) = XXX * 20,000 = 2 * XXX * 10^4
It doubles the first three numbers, and adds four zeroes to the end of it. Step 4 is currently irrelevant, because +1 before multiplying is merely the addition of another 250 (Step 5), which only affects the digits in the last four spaces which we've added to hold the last four digits.
So now we have 2 * XXX | 0000 + 250 (Step 4). The last four steps are simply adding the YYYY twice ( = 2*XXX | 2*YYYY + 250), getting rid of the 250, and halving the whole thing ( = XXX | YYYY)
And that is why math is boring.
There is then a need to guard against a temptation to overstate the economic evils of our own age, and to ignore the existence of similar, or worse, evils in earlier ages. Even though some exaggeration may, for the time, stimulate others, as well as ourselves, to a more intense resolve that the present evils should no longer exist, but it is not less wrong and generally it is much more foolish to palter with truth for good than for a selfish cause. The pessimistic descriptions of our own age, combined with the romantic exaggeration of the happiness of past ages must tend to setting aside the methods of progress, the work of which, if slow, is yet solid, and lead to the hasty adoption of others of greater promise, but which resemble the potent medicines of a charlatan, and while quickly effecting a little good sow the seeds of widespread and lasting decay. This impatient insincerity is an evil only less great than the moral torpor which can endure, that we with our modern resources and knowledge should look contentedly at the continued destruction of all that is worth having. There is an evil and an extreme impatience as well as an extreme patience with social ills.