# Math Is Fun Forum

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

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## #1 2016-08-28 09:33:06

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,143

### Quickies #10, Mathematics.

1.How many unique sets of 4 prime numbers exist for which the sum of the members of the set is 45 ?

2. Bobbym wrote on a gigantic piece  of paper all the numbers from 1 to 9999 . How many zero digits did he have to write down?

3. Find
.

4. Find x.

5. Which is greater?

[edited by admin](he latexed my post, gratitude to BOBBYM.

6. Find the sum of all perfect squares that divide 2016.

7. Find the greatest possible value of pq + r, where p, q, and r are (not necessarily distinct) prime numbers
satisfying pq + qr + rp = 2016.

8. Positive integers m and n are both greater than 50, have a least common multiple equal to 480, and have a
greatest common divisor equal to 12. Find m + n.

9. Bobbym is stuck fighting his nefarious lizard neighbors yet again though he has another weapon in his math... A LASER! He has 15 health, and the lizard has 20 health. He can deal any integer amount of damage from 1 to 4 and he has a 1/5 chance of dealing 3 damage, a 1/2 chance of dealing 1 damage, and a 1/5 chance of dealing  2 damage, and a 1/10 chance of deleaing 4 damage. Calculate the probability that bobbym will make it out alive, given that bobbym strikes first. The lizards have a 50% chance of dealing 1 damage, and a 50% chance of dealing 2 damage.
10. Find all continuous functions such that
and

Last edited by Mathegocart (2016-08-30 04:45:39)

The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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## #2 2016-08-28 09:36:57

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,316
Website

### Re: Quickies #10, Mathematics.

I think you're missing some information in #5.

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## #3 2016-08-28 10:22:10

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Quickies #10, Mathematics.

Hi;

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #4 2016-08-28 11:13:42

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,143

### Re: Quickies #10, Mathematics.

Fixed.(5)

The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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## #5 2016-08-28 11:14:58

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Quickies #10, Mathematics.

Are you sure?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #6 2016-08-28 11:18:34

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,143

### Re: Quickies #10, Mathematics.

bobbym wrote:

Hi;

Everything is correct, and I have fixed problem number 5.(VERIFIED.)

Last edited by Mathegocart (2016-08-28 11:18:46)

The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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## #7 2016-08-28 11:19:29

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Quickies #10, Mathematics.

Number 5 is rather easy, are you sure that is what you want? I need more for 9.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #8 2016-08-28 11:21:25

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,143

### Re: Quickies #10, Mathematics.

I meant $10^{30}$.

The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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## #9 2016-08-28 11:22:44

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Quickies #10, Mathematics.

Number 9 requires more information. What happens at the endpoints and what kind of damage does the large lizard do?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #10 2016-08-28 11:37:00

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,143

### Re: Quickies #10, Mathematics.

bobbym wrote:

Number 9 requires more information. What happens at the endpoints and what kind of damage does the large lizard do?

Didn
't I already specify what kind of damage he does? And how much damage you deal?

The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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## #11 2016-08-28 11:41:35

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Quickies #10, Mathematics.

Sorry, yes you did.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #12 2016-08-28 12:36:15

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,143

### Re: Quickies #10, Mathematics.

bobbym wrote:

Sorry, yes you did.

I just wanted to verify.

The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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## #13 2016-08-28 16:54:42

thickhead
Member
Registered: 2016-04-16
Posts: 1,086

### Re: Quickies #10, Mathematics.

Last edited by thickhead (2016-08-28 19:54:32)

{1}Vasudhaiva Kutumakam.{The whole Universe is a family.}
(2)Yatra naaryasthu poojyanthe Ramanthe tatra Devataha
{Gods rejoice at those places where ladies are respected.}

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## #14 2016-08-28 18:51:20

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Quickies #10, Mathematics.

Hi Mathegocart;

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #15 2016-08-28 19:56:49

thickhead
Member
Registered: 2016-04-16
Posts: 1,086

### Re: Quickies #10, Mathematics.

{1}Vasudhaiva Kutumakam.{The whole Universe is a family.}
(2)Yatra naaryasthu poojyanthe Ramanthe tatra Devataha
{Gods rejoice at those places where ladies are respected.}

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## #16 2016-08-28 23:58:34

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,143

### Re: Quickies #10, Mathematics.

bobbym wrote:

Hi Mathegocart;

The battle is, indeed, described in this manner.

The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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## #17 2016-08-29 04:25:48

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,143

### Re: Quickies #10, Mathematics.

thickhead wrote:

Wait, what? One of his acquaintances is named Liz?

The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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## #18 2016-08-29 06:33:22

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Quickies #10, Mathematics.

Not that I know of.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

## #19 2016-08-29 16:47:47

thickhead
Member
Registered: 2016-04-16
Posts: 1,086

### Re: Quickies #10, Mathematics.

(2)
No.of 0's in unit place=9999 div 10=999
No. of 0's in tens place=10*(9999 div 100)=990
No. of 0s in hundred place=100*(9999 div 1000)=900    Total=2889
No of any other digit=( 9999 div 10+1)+10*(9999 div 100+1)+100*(9999 div 1000+1)+1000*(9999 div 10000+1)=4000

{1}Vasudhaiva Kutumakam.{The whole Universe is a family.}
(2)Yatra naaryasthu poojyanthe Ramanthe tatra Devataha
{Gods rejoice at those places where ladies are respected.}

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## #20 2016-08-29 23:42:18

Mathegocart
Member
Registered: 2012-04-29
Posts: 2,143

### Re: Quickies #10, Mathematics.

thickhead wrote:

(2)
No.of 0's in unit place=9999 div 10=999
No. of 0's in tens place=10*(9999 div 100)=990
No. of 0s in hundred place=100*(9999 div 1000)=900    Total=2889
No of any other digit=( 9999 div 10+1)+10*(9999 div 100+1)+100*(9999 div 1000+1)+1000*(9999 div 10000+1)=4000

Strange, because with casework, I have gotten the same solution as bobbym has. I will check if I made a naive mistake, but..

The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

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## #21 2016-08-30 00:26:19

thickhead
Member
Registered: 2016-04-16
Posts: 1,086

### Re: Quickies #10, Mathematics.

My solution is same as bobbym's. Only i have added result for any  digit other than 0.

{1}Vasudhaiva Kutumakam.{The whole Universe is a family.}
(2)Yatra naaryasthu poojyanthe Ramanthe tatra Devataha
{Gods rejoice at those places where ladies are respected.}

Offline

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