Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**cooljackiec****Member**- Registered: 2012-12-13
- Posts: 178

anonimnystefy wrote:

Hi cooljackiec

I found that these numbers satisfy Q2.

I sort of see what you are doing here, but then again, I don't quite understand. We try to make sure that no numbers in our set are the arithemtic mean of two others. I've been suggested to use base 3, but I don't know how that would work.

EDIT: Turn our set into base 3 integers. Selecting those expressed with only 0 and 1 (base 3) gives us 2^k integers. I think this works, but I have to prove that this satisfies the condition of one number not being the AM of 2 others.

*Last edited by cooljackiec (2014-06-16 17:03:59)*

I see you have graph paper.

You must be plotting something

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

That is correct.

Now, think about what a sum of two such number looks like and what twice a such number looks like.

Also, did you see post #25?

*Last edited by anonimnystefy (2014-06-16 22:07:21)*

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline

**cooljackiec****Member**- Registered: 2012-12-13
- Posts: 178

The sum of two numbers (in base 3) will have a 2 digit?? Is that what you're saying?

also, 32 is not correct

I see you have graph paper.

You must be plotting something

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

It is correct that it will have the digit 2, but what's more imortant is that it will **always** have a 1. Compare that to a double of a number from the sequence.

Hm, you have the correct answer for Q1?

*Last edited by anonimnystefy (2014-06-17 04:42:52)*

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline

**cooljackiec****Member**- Registered: 2012-12-13
- Posts: 178

yea, i got the 2nd question, but not the 1st.

I see you have graph paper.

You must be plotting something

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

Do you know what the answer is to Q1?

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline

**cooljackiec****Member**- Registered: 2012-12-13
- Posts: 178

nope

I see you have graph paper.

You must be plotting something

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

Then, how do you know it's not 32?

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline

**cooljackiec****Member**- Registered: 2012-12-13
- Posts: 178

The decimal representation of m/n, where m and n are relatively prime positive integers and m<n, contains the digits 2, 5, and 1 consecutively, and in that order. Find the smallest value of n for which this is possible.

I see you have graph paper.

You must be plotting something

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 96,613

Hi;

**In mathematics, you don't understand things. You just get used to them.**

**If it ain't broke, fix it until it is.**

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

Hi bobbym

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline

**cooljackiec****Member**- Registered: 2012-12-13
- Posts: 178

I thought that 999 was the answer at first. 800 yields 0.25125. Maybe there's something else in the problem I didn't comprehend. I'm going to get some clarification

I see you have graph paper.

You must be plotting something

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

What happened for the first question?

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 96,613

Hi;

**In mathematics, you don't understand things. You just get used to them.**

**If it ain't broke, fix it until it is.**

Offline

**cooljackiec****Member**- Registered: 2012-12-13
- Posts: 178

so apparently, we can have 2513 and stuff. So like we just need 251 in order and then can have extra digits. 251 /999 is interesting, because 251 is close to 250, a divisor of 1000, which is cllose to 999.

Anyways, idk about the 1st quesiton

EDIT: we don't need to have a repeated decimal

*Last edited by cooljackiec (2014-06-20 08:35:21)*

I see you have graph paper.

You must be plotting something

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 96,613

so apparently, we can have 2513 and stuff

In that case we can get

**In mathematics, you don't understand things. You just get used to them.**

**If it ain't broke, fix it until it is.**

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

Hi bobbym

That seems the smallest so far.

Hi cooljackiec

Well, I asked you multiple times how you know the answer is not 32, without a respense.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 96,613

Hi anonimnystefy;

The older I get the more I demand rigor. Not in the answer like math types do, but in the question itself!

**In mathematics, you don't understand things. You just get used to them.**

**If it ain't broke, fix it until it is.**

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

Yes, I have noticed.

Do you think there is a smaller answer?

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 96,613

M does not think so. The last time I disagreed with M and I was right was in July 2001...

**In mathematics, you don't understand things. You just get used to them.**

**If it ain't broke, fix it until it is.**

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

Hm, how did M get that answer?

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 96,613

It just found a smaller one with an improvement in the logic.

and another one

and another

No mas?

**In mathematics, you don't understand things. You just get used to them.**

**If it ain't broke, fix it until it is.**

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

How did you get those?

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 96,613

Did you see the last one?

```
FindInstance[{m > 0, n > 0, Floor[1000 m/n] == 251, n < 127,
m != n}, {m, n}, Integers]
```

Got to go eat!

**In mathematics, you don't understand things. You just get used to them.**

**If it ain't broke, fix it until it is.**

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 15,937

Bon appétit!

That code seems to be slightly incomplete, but fortunately, it does not change the answer.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

Offline