ot needs some maths help

s1uggo72

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Oct 12, 2021
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I just saw one of those stupid math time wasting problems on youtube . The biggest issue is it was in Espanola (spanish I believe) any way the answer was
5#, which they seem to define as 5*3*2. I havent seen # listed as such . Of course we all know ! means the number times all of its numbers down to 1 (6! 6*5*4*3*2*1=) so what is this #? was I sleeping that day . I think it might mean multiply all the prime numbers starting with 5. TIA

 

LionJim

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Oct 12, 2021
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I just saw one of those stupid math time wasting problems on youtube . The biggest issue is it was in Espanola (spanish I believe) any way the answer was
5#, which they seem to define as 5*3*2. I havent seen # listed as such . Of course we all know ! means the number times all of its numbers down to 1 (6! 6*5*4*3*2*1=) so what is this #? was I sleeping that day . I think it might mean multiply all the prime numbers starting with 5. TIA


The answer is 30, which means that the answer must be 5#. I’ve never seen this symbol before (which probably doesn’t mean anything, as I have minimal expertise in number theory). Given that we gotta have 5# = 30, we can safely say that if p is a prime then p# is equal to the product of all primes less than or equal to p.
 

s1uggo72

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Oct 12, 2021
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The answer is 30, which means that the answer must be 5#. I’ve never seen this symbol before (which probably doesn’t mean anything, as I have minimal expertise in number theory). Given that we gotta have 5# = 30, we can safely say that if p is a prime then p# is equal to the product of all primes less than or equal to p.
thank you !! I had never seen that symbol before either, I did get 30 but that wasnt a choice. Maybe its a Mexican thing?
 
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psuro

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The answer is 30, which means that the answer must be 5#. I’ve never seen this symbol before (which probably doesn’t mean anything, as I have minimal expertise in number theory). Given that we gotta have 5# = 30, we can safely say that if p is a prime then p# is equal tothe product of all primes less than or equal to p.

33- (3/3)-2 ---->33 - 1 - 2 = 30.

emma stone math GIF by Saturday Night Live
 

PSU Mike

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The answer is 30, which means that the answer must be 5#. I’ve never seen this symbol before (which probably doesn’t mean anything, as I have minimal expertise in number theory). Given that we gotta have 5# = 30, we can safely say that if p is a prime then p# is equal to the product of all primes less than or equal to p.
I think it should be defined as n# = n(n+1) 😛
 
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LionJim

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30 wasn’t a choice though. 5# was though. I never saw the # notation before
Process of elimination: Because you can determine that none of the other options were equal to 30, 5# is the only possible answer. Thus 5#=30.
 
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AvgUser

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I understand how factorials are used.
Where and why on earth is an N# ever, ever, ever used?
 
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LionJim

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I understand how factorials are used.
Where and why on earth is an N# ever, ever, ever used?
Number theory. For example, you can use p# to prove that you can get strings of consecutive non prime numbers which can be as long as you like.

Example: 8 ,9 ,10 are three consecutive nonprimes. 32, 33, 34, 35, 36 five consecutive nonprimes. 212, 213, 214, 215, 216, 217, 218 seven consecutive nonprimes. There are infinitely many primes, but you can find a string of 100,000,000,000,000,000,000 consecutive nonprimes. The proof (quite simple) uses p#.

Idea of how it works:

7# = 210. This is divisible by every prime less than or equal to 7.

7# + 2 is divisible by 2, so a nonprime.
7# + 3 is divisible by 3
7# + 4 is divisible by 2
7# + 5 is divisible by 5
7# + 6 is divisible by 2
7# + 7 is divisible by 7.
7# + 8 is divisible by 2. So you've got seven consecutive nonprimes.
 
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s1uggo72

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Oct 12, 2021
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Process of elimination: Because you can determine that none of the other options were equal to 30, 5# is the only possible answer. Thus 5#=30.
Yes well true but then I thought is # a real thing or something made up just for this question
 

LionJim

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Oct 12, 2021
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Number theory. For example, you can use p# to prove that you can get strings of consecutive non prime numbers which can be as long as you like.

Example: 8 ,9 ,10 are three consecutive nonprimes. 32, 33, 34, 35, 36 five consecutive nonprimes. 212, 213, 214, 215, 216, 217, 218 seven consecutive nonprimes. There are infinitely many primes, but you can find a string of 100,000,000,000,000,000,000 consecutive nonprimes. The proof (quite simple) uses p#.

Idea of how it works:

7# = 210. This is divisible by every prime less than or equal to 7.

7# + 2 is divisible by 2, so a nonprime.
7# + 3 is divisible by 3
7# + 4 is divisible by 2
7# + 5 is divisible by 5
7# + 6 is divisible by 2
7# + 7 is divisible by 7.
7# + 8 is divisible by 2. So you've got seven consecutive nonprimes.
Actually, you can use p# to prove that there are infinitely many primes. The Fundamental Theorem of Arithmetic (FTA) says that you can factor every natural number larger than 1 into a unique product of primes. This implies that every natural number greater than 1 is divisible by a prime.

Suppose there were only a finite number of primes, then you’ll have a largest prime P. In this case, P# would be the product of every single prime. Then P# + 1 is not divisible by any prime less than or equal to P (because the remainder would always be 1), that is, not divisible by any prime. This contradicts FTA.
 

Woodpecker

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Oct 7, 2021
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Number theory. For example, you can use p# to prove that you can get strings of consecutive non prime numbers which can be as long as you like.

Example: 8 ,9 ,10 are three consecutive nonprimes. 32, 33, 34, 35, 36 five consecutive nonprimes. 212, 213, 214, 215, 216, 217, 218 seven consecutive nonprimes. There are infinitely many primes, but you can find a string of 100,000,000,000,000,000,000 consecutive nonprimes. The proof (quite simple) uses p#.

Idea of how it works:

7# = 210. This is divisible by every prime less than or equal to 7.

7# + 2 is divisible by 2, so a nonprime.
7# + 3 is divisible by 3
7# + 4 is divisible by 2
7# + 5 is divisible by 5
7# + 6 is divisible by 2
7# + 7 is divisible by 7.
7# + 8 is divisible by 2. So you've got seven consecutive nonprimes.
So, when you say nonprime, you mean like Netflix?
 

leinbacker

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Oct 13, 2021
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Maybe 5# means multiply the numbers in a Fibonacci sequence up to 5.
 

step.eng69

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The answer is 30, which means that the answer must be 5#. I’ve never seen this symbol before (which probably doesn’t mean anything, as I have minimal expertise in number theory). Given that we gotta have 5# = 30, we can safely say that if p is a prime then p# is equal to the product of all primes less than or equal to p.

thank you !! I had never seen that symbol before either, I did get 30 but that wasnt a choice. Maybe its a Mexican thing?

33- (3/3)-2 ---->33 - 1 - 2 = 30.
Never saw this TV series, I stayed up until 3am this morning, laughing like a fool thinking about LionJim as a young youth.
thought this show was hilarious.

"Lord look after my son, don’t let him get stuffed in a gym bag”





 
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LionJim

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Never saw this TV series, I stayed up until 3am this morning, laughing like a fool thinking about LionJim as a young youth.
thought this show was hilarious.

"Lord look after my son, don’t let him get stuffed in a gym bag”






You never saw this before? Not a bad way to waste time.

I was nothing like Sheldon. It was just an accident I got into mathematics. It was the only class at Penn State where I could take my own notes, which is ironic because I learned much later that serious math students shouldn’t take notes, as they have a perfectly fine textbook to rely on. I got 700 on my math SAT but if I hadn’t become deaf, or hadn’t gone to Penn State, I would most likely have ended up a literature professor. Oh my God, what a bullet I dodged. I love my lit but it would have been an ordeal teaching it.

Anyway, it’s a funny show.
 

LionJim

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Oct 12, 2021
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Here’s a story I haven’t told before, I suppose because it puts my father, who I loved dearly, in a bad light.

I became deaf in kindergarten (spinal meningitis outbreak, four other kids in my school died, I’m told). So starting in first grade I would commute from Levittown to Fairmont in Philadelphia, to the Martin Bache School, a block from the Eastern State Penitentiary. It was an oral school, no sign language, and I was a superstar there. (My parents were very well educated, books everywhere.) Plus, I could already speak clearly. (Another reason I haven’t brought this up before. Most of my classmates were born deaf and I really had an unfair advantage as far as being able to speak was concerned. And my Irish Catholic spinster teachers were all very impressed with my Irish Catholic Jesuit priest uncle. But I digress.) it was my mother’s fondest hope that sooner rather than later I’d be able to be mainstreamed in our local schools. She really really really did not want me to grow up in the Deaf world. Anyway, my math was too good for my teachers to keep up with so in the spring before I turned ten it was arranged that I’d take an algebra class at Masterman JHS, three or so blocks away from Martin, starting in the fall. My mom died a week before school started that year. I go to class at Masterman and I’m totally lost, getting Cs and Ds, not being able to understand the teacher, totally overwhelmed. The teacher, most likely motivated by pity for this bereaved deaf boy, gives me an A+ and says that I’m the best student he’s ever seen. And so my dad, of course, thinks that I’m ready to be mainstreamed and I’m put into 8th grade in Sandburg JHS, skipped a grade. What the hell am I supposed to tell my father? That the teacher was flat out lying? (Dad was going through a horrible time himself, of course. Five motherless kids, the oldest was 12.) Anyway, I started going to the local school and nobody could understand why this supposed math genius couldn’t do better than a C in algebra. And I had zero support, nobody knew what to do with a deaf kid. Anyway…I guess it all worked out in the end but boy was I a misfit. It wasn’t fair to anyone, my teachers or my classmates.
 

PSU Mike

Well-known member
Oct 6, 2021
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Here’s a story I haven’t told before, I suppose because it puts my father, who I loved dearly, in a bad light.

I became deaf in kindergarten (spinal meningitis outbreak, four other kids in my school died, I’m told). So starting in first grade I would commute from Levittown to Fairmont in Philadelphia, to the Martin Bache School, a block from the Eastern State Penitentiary. It was an oral school, no sign language, and I was a superstar there. (My parents were very well educated, books everywhere.) Plus, I could already speak clearly. (Another reason I haven’t brought this up before. Most of my classmates were born deaf and I really had an unfair advantage as far as being able to speak was concerned. And my Irish Catholic spinster teachers were all very impressed with my Irish Catholic Jesuit priest uncle. But I digress.) it was my mother’s fondest hope that sooner rather than later I’d be able to be mainstreamed in our local schools. She really really really did not want me to grow up in the Deaf world. Anyway, my math was too good for my teachers to keep up with so in the spring before I turned ten it was arranged that I’d take an algebra class at Masterman JHS, three or so blocks away from Martin, starting in the fall. My mom died a week before school started that year. I go to class at Masterman and I’m totally lost, getting Cs and Ds, not being able to understand the teacher, totally overwhelmed. The teacher, most likely motivated by pity for this bereaved deaf boy, gives me an A+ and says that I’m the best student he’s ever seen. And so my dad, of course, thinks that I’m ready to be mainstreamed and I’m put into 8th grade in Sandburg JHS, skipped a grade. What the hell am I supposed to tell my father? That the teacher was flat out lying? (Dad was going through a horrible time himself, of course. Five motherless kids, the oldest was 12.) Anyway, I started going to the local school and nobody could understand why this supposed math genius couldn’t do better than a C in algebra. And I had zero support, nobody knew what to do with a deaf kid. Anyway…I guess it all worked out in the end but boy was I a misfit. It wasn’t fair to anyone, my teachers or my classmates.
Thanks for sharing, Jim!
 

step.eng69

Well-known member
Oct 12, 2021
2,836
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Here’s a story I haven’t told before, I suppose because it puts my father, who I loved dearly, in a bad light.

I became deaf in kindergarten (spinal meningitis outbreak, four other kids in my school died, I’m told). So starting in first grade I would commute from Levittown to Fairmont in Philadelphia, to the Martin Bache School, a block from the Eastern State Penitentiary. It was an oral school, no sign language, and I was a superstar there. (My parents were very well educated, books everywhere.) Plus, I could already speak clearly. (Another reason I haven’t brought this up before. Most of my classmates were born deaf and I really had an unfair advantage as far as being able to speak was concerned. And my Irish Catholic spinster teachers were all very impressed with my Irish Catholic Jesuit priest uncle. But I digress.) it was my mother’s fondest hope that sooner rather than later I’d be able to be mainstreamed in our local schools. She really really really did not want me to grow up in the Deaf world. Anyway, my math was too good for my teachers to keep up with so in the spring before I turned ten it was arranged that I’d take an algebra class at Masterman JHS, three or so blocks away from Martin, starting in the fall. My mom died a week before school started that year. I go to class at Masterman and I’m totally lost, getting Cs and Ds, not being able to understand the teacher, totally overwhelmed. The teacher, most likely motivated by pity for this bereaved deaf boy, gives me an A+ and says that I’m the best student he’s ever seen. And so my dad, of course, thinks that I’m ready to be mainstreamed and I’m put into 8th grade in Sandburg JHS, skipped a grade. What the hell am I supposed to tell my father? That the teacher was flat out lying? (Dad was going through a horrible time himself, of course. Five motherless kids, the oldest was 12.) Anyway, I started going to the local school and nobody could understand why this supposed math genius couldn’t do better than a C in algebra. And I had zero support, nobody knew what to do with a deaf kid. Anyway…I guess it all worked out in the end but boy was I a misfit. It wasn’t fair to anyone, my teachers or my classmates.
I am So sorry to hear about your mom dying at your young age.
Thomas
 
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