Help! - maths

[Clinton1]

A forum I am trying to get one has a secret question I can not get past.
How many days in February 1803 PLUS February 1716, now add -21, and take the square root.
I am so stumped!
Can anyone help?

[Fuzzie]

28+29-21=36
root(36)=6

[ian]

:whs:

[cava]

:wts:

[rwbuild]

The logic behind it is easy, it has to be a std 28 day February + a leap year to get a total that has a natural square root ie: 28 + 28 = 56 - 21 = 35, no natural sq rt
29 + 29 = 58 - 21 = 37, no natural sq rt

The nominated years are only to put you off track for confusions sake

(edit my bad maths) :-

Still no whole number natural sq root

[BobL]

question doesn't say anything a natural square root.


The logic behind it is easy, it has to be a std 28 day February + a leap year to get a total that has a natural square root ie: 28 + 28 = 56 - 21 = 55, no natural sq rt
29 + 29 = 58 - 21 = 57, no natural sq rt

Actually its 35, and 37 and of course they have square roots, 6.08276253029822...... and 5.91607978309962. . . . . . .

[A Duke]

Hi,
The years are not just to confuse, if the year is dividable by 4 it is a leap year. Not sure off hand when the modern calendar came about so could still be a trap. :D
Regards

[Bohdan]

1583 is the first full year of the Gregorian calendar (http://www.infoplease.com/spot/gregorian1.html). 1753 was the first full year in which the U.S. (then a British colony) began using the Gregorian calendar.

[derekcohen]

I'd say 6 as well. What are we missing, if at all?

And do you really want to be on a forum that cannot do maths as well as we can? :)

Regards from Perth

Derek

[Fuzzie]

And do you really want to be on a forum that cannot do maths as well as we can? :)
Clinton hasn't told us yet if 6 is indeed the correct answer. In any case I assume the question is to determine if the answerer is a human and not a bot; not specifically meant to trick and trap. I'd prefer to be on a forum where the humans predominate. Many algorithms do maths quicker and more accurately than I do, even though I sometimes think in reverse polish. :rolleyes:

[ian]

Many algorithms do maths quicker and more accurately than I do, even though I sometimes think in reverse polish. :rolleyes:out of interest, when did you buy your first HP calculator?

[ian]

Hi,
The years are not just to confuse, if the year is dividable by 4 it is a leap year. Not sure off hand when the modern calendar came about so could still be a trap. :D
Regardsso to be really tricky, the question should have been...

How many days in February 1800 PLUS February 1716, now add -21, and take the square root.

[ian]

question doesn't say anything a natural square root.

its 35, and 37 and of course they have square roots, 6.08276253029822...... and 5.91607978309962. . . . . . .but neither are particularly useful as a bot trap. where do you truncate the number ?

SQRT(35) = 5.9, or 5.92, or 5.916, etc. to a machine 5.91608 is not the same as 5.916080

[Chesand]

so to be really tricky, the question should have been...

How many days in February 1800 PLUS February 1716, now add -21, and take the square root.

The answer is still 6.

[Fuzzie]

out of interest, when did you buy your first HP calculator?

Never, I've always played with real computers. :)
My first introduction to reverse polish was in 1971 learning Fortran from McCraken's manual.
I think I wrote my own first usable RP calculator program in about 1981 on a Prime computer.

[Fuzzie]

whoops

[ian]

so to be really tricky, the question should have been...

How many days in February 1800 PLUS February 1716, now add -21, and take the square root.


The answer is still 6.nope

1800 wasn't a leap year. neither was 1900, nor will 2100 be a leap year.

Century years need to be divisible by 400 before they are leap years. That is the essential innovation of the Gregorian Calendar.

[Oldgreybeard]

I think I wrote my own first usable RP calculator program in about 1981 on a Prime computer.

Crickey a Prime computer - now that brings back memories. I worked for McDonnell Douglas in the 1980s developing and installing health computing systems at a number of Australian and NZ hospitals. All our software was written Basic though and all dates and other Americanisms had to be converted manually to the Australian format and spelling.

However did get to spend 40 weeks in St Louis at someone's expense.

And yes the answer is 6

Bob

[Chesand]

You are correct that 1800 was not a leap year but 1716 is divisible by 4

[rrich]

Never, I've always played with real computers. :)
My first introduction to reverse polish was in 1971 learning Fortran from McCraken's manual.
I think I wrote my own first usable RP calculator program in about 1981 on a Prime computer.

OMG!
McCracken! About 1969 and I used the Fortran II version. As we upgraded to Fortran IV, McCracken just didn't seem to do it with IV.

And, the Prime. The nicest thing that I could say about the Prime was that it sucked Charles River water.

The Prime systems were desirable for network control systems because they supported X.25 directly into the CPU. We used them to run Telenet. (US VAN or Value Added Network which was based on X.25. We later evolved Telenet, a.k.a. Sprintnet, into what is now the Internet in the US. ) We sold a lot of international X.25 networks but I don't remember if we sold a network to Telstra.

Thank you for the comment about RPN and Fortran. When thinking about it after all these years, RPN is rather obvious now.

[Fuzzie]

I didn't mean to hijack the thread. :-
... so I'll refrain from trying to remember why I liked working for PR1ME. :)

[AlexS]

I'm another one who used McCracken, back about 1970 IIRC.
An organisation I worked for in the late 70s looked at buying a Prime. They were very big on hospitality - had a few nice lunches on them. Also remember in their Melbourne office, they had receptionists who were twin sisters who dressed the same - most attractive they were, too.

[ian]

An organisation I worked for in the late 70s looked at buying a Prime. They were very big on hospitality - had a few nice lunches on them. Also remember in their Melbourne office, they had receptionists who were twin sisters who dressed the same - most attractive they were, too.now that, is worthy of further comment

[Big Shed]

now that, is worthy of further comment


It is also wildly off-topic.

[AlexS]

It is also wildly off-topic.Yeah, but...:D

[ian]

Yeah, but...:D
the last 20 posts are OT.

but does it really matter?

[Fuzzie]

Unfortunately before my time, must have been during the Lionel Singer period. But entertainment and the reception desk were still memorable during later years :2tsup:. PR1ME always rated highly on equality and acceptance of eccentricities as well. But that's getting way off topic. If only Clinton's original challenge had to do with some sort of prime number calculation.

I wonder if Clinton ever got registered on his other forum?

[ian]

If only Clinton's original challenge had to do with some sort of prime number calculation.how about

find the missing number (x)
SQRT (169)
SQRT (25)
SQRT (x)

[Chesand]

x = 1

[AlexS]

x = 1
Better yet, x=-1

[Ari2]

how about

find the missing number (x)
SQRT (169)
SQRT (25)
SQRT (x)

I go with 4.

[Fuzzie]

Although 1,5,13 is a recognized sequence, being given only 2 values of a sequence I would argue there is actually no correct arithmetic answer as there is nothing other than elegance to solve for. Unlike the original challenge.

[Chesand]

3 fits in that sequence also therefore x could equal 9

[ozka]

Now, how does one 'add' -21?

[Chesand]

The minus sign means that you subtract 21 from the other total.

So in the original question 28 + 29 = 57 57 - 21 = 36 The square root of 36 is 6 (6 x 6 = 36)

[ian]

If only Clinton's original challenge had to do with some sort of prime number calculation.


how about

find the missing number (x)
SQRT (169)
SQRT (25)
SQRT (x)


Although 1,5,13 is a recognized sequence, being given only 2 values of a sequence I would argue there is actually no correct arithmetic answer as there is nothing other than elegance to solve for. Unlike the original challenge.
Perhaps too elegant a challenge.

I was picking up Fuzzie's request for a challenge involving prime numbers.

5 and 13 are both prime, the third number, while not a prime involves solving a right triangle.

[rrich]

It is also wildly off-topic.


Yeah, but...:D

Oh, pictures please! :U

[rrich]

how about

find the missing number (x)
SQRT (169)
SQRT (25)
SQRT (x)

So X would be 9.

A better scenario would be;
SQRT (169)
SQRT (121)
SQRT (49)
SQRT (25)
SQRT (x) Where x=9
Or the SQRT results 13, 11, 7, 5, and 3

OK, the horse is dead.

[ian]

Better yet, x=-1
I'm fairly certain that i is not a prime number

[ian]

So X would be 9.

A better scenario would be;
SQRT (169)
SQRT (121)
SQRT (49)
SQRT (25)
SQRT (x) Where x=9
Or the SQRT results 13, 11, 7, 5, and 3

OK, the horse is dead.Now that is an elegant prime number problem

[Fuzzie]

Perhaps for that challenge the given sequence should just be x,25,49,121,169. Providing the sqrt() clue being redundant?

BTW, Ian your challenge beat me. The sqrt() function actually made it solving the problem given 3 elements not 2! My bad.

[Chesand]

5 and 13 are both prime, the third number, while not a prime involves solving a right triangle.

12.

5, 12, 13 where 5 and 12 are the sides of a triangle adjoining the right angle and 13 is the hypotenuse.

In a right angled triangle, the sum of the squares of the 2 sides equals the square of the hypotenuse. (5x5) + (12x12) = (13x13)

It is along time since I learned that t high school but has stuck as has 3,4,5 for the same purpose.

[Ari2]

I go with 4.

4 fits because it follows the Fibonacci sequence. 0,1,1,2,3,5,8,13,21....

13 sqrd = 169
5 sqrd = 25
2 sqrd = 4

So it works if you skip the 3 and 8 in the sequence.

:)

[Grumpy John]

I have been following this thread with interest. I admit I'm lost with all the prime and SQRT lingo, but I'll make my contribution.
When I was building and servicing CNC machines I had to learn Hex.

First 10 prime numbers in Hex.
2
3
5
7
B
D
11
13
17
1D

And in Octal
2
3
5
7
13
15
21
23
27
35

[ian]

12.

5, 12, 13 where 5 and 12 are the sides of a triangle adjoining the right angle and 13 is the hypotenuse.

In a right angled triangle, the sum of the squares of the 2 sides equals the square of the hypotenuse. (5x5) + (12x12) = (13x13)

It is along time since I learned that t high school but has stuck as has 3,4,5 for the same purpose.

That's the answer I was looking for.

[AlexS]

When I was trying to explain hexadecimal to my wife (a futile task, of course) I resorted to using the terms sixteenty and thirtytwoty.:D

[Grumpy John]

Never, I've always played with real computers. :)
My first introduction to reverse polish was in 1971 learning Fortran from McCraken's manual.
I think I wrote my own first usable RP calculator program in about 1981 on a Prime computer.

I don't remember what my first calculator was, but I know it could spell hELL0 and ShELL :D

[BobL]

I don't remember what my first calculator was, but I know it could spell hELL0 and ShELL :D

I remember setting up equations that would result in 80085

[Grumpy John]

I remember setting up equations that would result in 80085

It took a second or two, then the penny dropped:clap3:.

[rrich]

I remember setting up equations that would result in 80085

A sick bunch are we.

[A Duke]

Hi,
I remember one were the answer described the young lady who's measurements were entered as 80087355.
:wink:
Regards