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

You are not logged in.

- Topics: Active | Unanswered

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

Good!

Example:

T[sub]4[/sub] means that you need to get the 5th triangular number because T[sub]0[/sub] is 1, the first triangular number.

Okay!

Next question:

Numbers 3 4 5

Operations T +

Answer 46

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

Hi;

The first triangular number is 0, so T0 = 0.

But using your definition we can say

T3 + T4 + T5 = 46

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

Oh. My classmate taught me that T thing.

Number 14 28 42

Operation + - [sup]2[/sup]

Answer 1764

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

42^2 = 1764

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

New edition :

P * C.P = 5

P = Prime

C = Composite

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

it can't be.

5 = 5*1 and there isn't any other factorisation

'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'

I'm not crazy, my mother had me tested.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

Hi julianthemath;

5 only has the factorization of 5 x 1. 1 is not composite or prime. Please post another problem this one has no solution.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

C.P means decimal number. Try again.

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**mathdad****Member**- Registered: 2013-04-13
- Posts: 21

julianthemath wrote:

New edition :

P * C.P = 5

P = Prime

C = Composite

Still not possible.

All P are such that P > 1. The smallest P is 2. And, the smallest C such that C > 0 is 4

Thus P * C.P >= 2 * 4.d = 8.0 + 2d (where 2d is 2 times the decimal part)

If you were trying to go for 2 * 2.5, then the 2 in 2.5 is not Composite, it is Prime.

*Last edited by mathdad (2013-04-22 09:04:17)*

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

Oh, well.

No answers, no points.

Wanna ask, mathdad? bobbym? Or just keep me?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

Hi;

Okay, let me see the answer. Please hide the answer cause someone else may still want to work on it.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

81 + X - 4 = 85

Solve for X.

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

Hi;

Thanks for the answer.

X = 0

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

Again!

81 + X - 4 = 85

You might have an error.

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

H;

81 + X - 4 = 85

Add 4 to both sides:

81 + X = 89

Subtract 81 from both sides.

X = 8

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

Wow.

1777 - 777 + 777 * 777 = ?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

604729 is the answer.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

Wow!

This time, there are points.

X + X = X

What makes this impossible to answer? 30 points

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

Nothing, X can be 0.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

Oh. How do you like my signature? Funny, right?

Bobbym - 30

3 6 9 15 ? What is the fifth number?

*Last edited by julianthemath (2013-04-25 21:01:50)*

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

I like 21 as the nest number.

I worked a long time on bobbym - 30 but could not come up with anything.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

Oh.

Bobbym - 60

If China has a population of 1,234,567,890,

India 123,456,789

USA 12,345,678

Indonesia 1,234,567

What is the population of Brazil?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,414

Is it 123 456 ?

How are the chickenpox?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,247

No. I didn't have it, my cousins do. The start of the infection was during the afternoon I came home after my last exams. And now, some of my cousins are having the chickenpox. So, I just need to stay inside.

Yes. It is 123,456.

Bobbym - 90

If Gangnam style were a country (by no. of views), what rank is it?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline