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

You are not logged in.

- Topics: Active | Unanswered

**gAr****Member**- Registered: 2011-01-09
- Posts: 3,479

Hi Agnishom,

*Last edited by gAr (2013-01-15 22:51:14)*

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense" - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

Offline

Thnk you gAr

One question, if I get such a question in an exam shall I have to write out all the possible combinations?

*Last edited by Agnishom (2013-01-16 01:42:40)*

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**gAr****Member**- Registered: 2011-01-09
- Posts: 3,479

Hi,

I think you can only mention about the remainders, number of such combinations and the pigeonhole principle.

But I'm a bit confused about the minimum of such numbers required to guarantee that no three numbers form a cube, because we can see that taking three consecutive numbers there is also a cube.

Anyway, a good question, is it from a question paper?

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense" - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

Offline

Yes. It is

*Last edited by Agnishom (2013-01-16 14:21:40)*

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**gAr****Member**- Registered: 2011-01-09
- Posts: 3,479

Ok, thanks for the questions..

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense" - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 89,150

Hi Agnishom;

What is the title pf the book?

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

**I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.**

Offline

Title pf means?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**gAr****Member**- Registered: 2011-01-09
- Posts: 3,479

I think he typed "pf" instead of "of"..

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

Offline

Well

I am not taking them from a book instead I am asking them from various olympiad questions

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 89,150

Hi gAr and Agnishom;

I have the flu and I am not as sharp as usual. I did mean of, sorry.

What I meant is Olympiad problems have numbers and state what Olympiad they are from. They also have answers to them that I can look up so you can study them. gAr's answer is the one I was working on also but he got there first.

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

**I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.**

Offline

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 89,150

Hi Agnishom;

I have downloaded some more pdfs but so far nothing to help us.

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

**I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.**

Offline

**gAr****Member**- Registered: 2011-01-09
- Posts: 3,479

Hi bobbym,

How are you now?

Hi Agnishom,

Thanks for the links.

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 89,150

Hi gAr;

Not much better, kind of tired.

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

Offline

**gAr****Member**- Registered: 2011-01-09
- Posts: 3,479

Hi,

Oh, take some rest..

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 89,150

Hi;

That is what I am going to do.

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

Offline

bobbym wrote:

I have downloaded some more pdfs but so far nothing to

helpus.

Regarding what?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 89,150

Hi Agnishom;

Solutions for RMO's and that sort of thing.

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

Offline

Question 11: **How many digits does 5^44 have?**

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 89,150

10^x = 5^44

Take the common log of both sides

x = 44 log(5)

x = 30.7546

So we have

10^(.7546) * 10 ^30

5.48 * 10^30 moves the decimal point 30 places to the right. So it has 31 digits.

*Last edited by bobbym (2013-02-09 15:25:40)*

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

Offline

Actually, they said "without using a calculator"

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,612

Hi Agnishom

You can still use that.

The number of digits of a number is floor(log_10(that number))+1.

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

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 89,150

Hi;

You can also get quite close using:

*Last edited by bobbym (2013-02-09 23:19:13)*

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

Offline

anonimnystefy wrote:

Hi Agnishom

You can still use that.

The number of digits of a number is floor(log_10(that number))+1.

Thats correct

Now, how do I do that to 5^44 without a calculator?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,612

Well you can approximate the logarithm...

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

Offline