# Some problems to solve

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Thread starter 15 years ago
#1
1. How many factors, which themselves are factors of 3, does the number 241920 have? (not including 3 itself)

2. The difference and product of two consecutive primes are added together. Is the number produced a prime itself?

3. Evaluate the series 3 + 7 + 11 + ... + 201 + 205.

4. Find the value of (6! + 5!)/5!

5. Simplify: [(n+1)!/(n-1)!]!
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15 years ago
#2
(Original post by mik1a)
1. How many factors, which themselves are factors of 3, does the number 241920 have? (not including 3 itself)
Only factors of 3 are 1 and 3, so there's only 1 factor of 241920 that is also factor of 3 (except for 3 itself) and that's 1!!! (Do you mean multiples of 3??)
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15 years ago
#3
(Original post by mik1a)
2. The difference and product of two consecutive primes are added together. Is the number produced a prime itself?
7 and 11 are 2 consecutive primes, product 77, difference 4, sum of these 2 is 81 = 9*9 so no

4. 6 + 1 = 7

5. [(n+1)n]!
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15 years ago
#4
(Original post by mik1a)
2. The difference and product of two consecutive primes are added together. Is the number produced a prime itself?
7 and 11 are two consecutive primes.
Difference=4
11*7=77
77+4=81 which is not prime (facors 9, 3 etc)

(Darn!-Bezza got there before me....sorry didn't see you there!)
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15 years ago
#5
(Original post by mik1a)
1. How many factors, which themselves are factors of 3, does the number 241920 have? (not including 3 itself)

2. The difference and product of two consecutive primes are added together. Is the number produced a prime itself?

3. Evaluate the series 3 + 7 + 11 + ... + 201 + 205.

4. Find the value of (6! + 5!)/5!

5. Simplify: [(n+1)!/(n-1)!]!
For q. 2, it can be, but isn't neccessarily, namely 5, 3 satisfy it, but 7,11 does not.
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15 years ago
#6
(Original post by mik1a)
1. How many factors, which themselves are factors of 3, does the number 241920 have? (not including 3 itself)

2. The difference and product of two consecutive primes are added together. Is the number produced a prime itself?

3. Evaluate the series 3 + 7 + 11 + ... + 201 + 205.

4. Find the value of (6! + 5!)/5!

5. Simplify: [(n+1)!/(n-1)!]!

I don't see the pattern in questions 3. Were it an AP with common difference d, then neither 201 or 205 would be terms in the series as each term must satisfy 4n-1.
0
15 years ago
#7
(Original post by mik1a)
1. How many factors, which themselves are factors of 3, does the number 241920 have? (not including 3 itself)

2. The difference and product of two consecutive primes are added together. Is the number produced a prime itself?

3. Evaluate the series 3 + 7 + 11 + ... + 199 + 203.

4. Find the value of (6! + 5!)/5!

5. Simplify: [(n+1)!/(n-1)!]!
first term 3, common difference 4, using formula for arithmetic progression we get:

5253 for n=51
0
15 years ago
#8
(Original post by mik1a)

4. Find the value of (6! + 5!)/5!

(1x2x3x4x5x6)+(1x2x3x4x5)/(1x2x3x4x5)

(1x2x3x4x5)(1+6)/(1x2x3x4x5)

7
0
15 years ago
#9
(Original post by mik1a)

5. Simplify: [(n+1)!/(n-1)!]!

[n!(n+1)/(n-1)!]!

[(n-1)!(n(n+1))/(n-1)!]!

[n(n+1)]!
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15 years ago
#10
do u guys realise just how sad u are sat at ur computer at 1:24 in the afternoon doing maths!
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15 years ago
#11
(Original post by Economics)
do u guys realise just how sad u are sat at ur computer at 1:24 in the afternoon doing maths!

Excuse me im at work developing a website for london met university...and its lunch time so i just thought i would do wonder around UKL!
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Thread starter 15 years ago
#12
2. The difference and product of two consecutive numbers which are prime are added together. Is the number produced a prime itself?

3. Evaluate the series 3 + 7 + 11 + ... + 199 + 203.
Corrected problems (sorry!)
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Thread starter 15 years ago
#13
(Original post by Economics)
do u guys realise just how sad u are sat at ur computer at 1:24 in the afternoon doing maths!
Whatever, your user name is Economics.
0
15 years ago
#14
(Original post by mik1a)
Whatever, your user name is Economics.
and your point is?
0
15 years ago
#15
(Original post by Economics)
and your point is?
My point is going to be: you got banned for a day yesterday for posting such crap - haven't you learnt?
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15 years ago
#16
(Original post by Bezza)
My point is going to be: you got banned for a day yesterday for posting such crap - haven't you learnt?
its not crap
0
15 years ago
#17
do u guys realise just how sad u are sat at ur computer at 1:24 in the afternoon doing maths!
I think people who who write posts in text gibberish, trying to mock people who enjoy doing maths problems, are the real sad ones!
0
15 years ago
#18
(Original post by Economics)
its not crap
no - it's worse than crap it's spam
0
15 years ago
#19
(Original post by nollaig)
I think people who who write posts in text gibberish, trying to mock people who enjoy doing maths problems, are the real sad ones!
here, here.......that adds you to the list
0
15 years ago
#20
(Original post by Economics)
here, here.......that adds you to the list
so you do want to get banned again?
0
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