Items tagged with numbers


Hello everybody,

I have an interesting math problem, here it is:


Add the following operators: +, -, * in the middle of the following string 123456789 to get the final result: 2016

The operators can be added randomly at any place, it isn't necessarily placed in between single numbers.


To convince your result, one should provide the code or explain explicitly your method.

Have fun!!!!



Another application for the study of rational numbers in operations, generating fraction, etc.

(in spanish)




So if i have a list of numbers X:=[1, 3, 8, 9, 10] for example, how do i calculate the Σx*ln(x) for each x in X ?


im certain it must be possible but i cant figure out how.


thanks for your time :)

See subject. Via Google I only found links for converting from decimal to binary. But how do I write a binary number in the first place? I don't have a decimal to convert from, I have long binaries to start with! Which I don't want to convert to decimal, since I want binaries as output too.

Greetings to all!

Recently I encouter the following issue:

Maple (version 17) coudn't recognize that 20.0 equals with 20 and with 20.00. Believe me, this is very annoying!

Do I miss something? Is there any command that do the trick?


Thank you!

Giorgos K.



What is the command to get a sequence of the first twenty prime numbers

hello. before I used Mapple 15. But then I`ve run Mapple 16 and now I`ve a problem. I can`t use this program. I open the program, everthing is in the rule, but if I want to write any mathemathical function, or a letter, such as- x or x+2, the program does`t give any reaction. program only gives reaction the numbers.

Please, help me. (my english isn`t very good, and I don`t know I`ve explained my opinion).


this question has been asked several times here already accoruding to the search function, but I didn't find an actual answer to it.

My Maple 15 gives outlarge numbers without scientific notation, so even 10^20 would be displayed as 1000....000  (20 zeroes). It seems like this is not the standard, so at one point I might have changed the way Maple displays the output, and cannot remember anymore how.

How can I tell Maple to display the output in scientiffic notation, and how can I set up the threshold of powers of ten, when this is done. (so that e.g. 100 still gets disaplyed as 100, and not as 1*10^2, but anything above gets displayed in scientific notation).

I know that I can right click on the output to change it's display form. But I want to change this generally, so I dont have to do this for any single numerical output I get.

I use Maple 15, running in Mac OS.

Thanks for help!

I have an expression (with important physical meaning), I want to transform all the nasty numbers into scientific notations like transforming 203475439 to 2.0347e8.... anyone could help? thanks



Here is an example I have,

> evalf(sum(Zeta(p-2.)*2.9^p/GAMMA(.5000000000*p+1.), p = 4 .. infinity))

The Maple just returns me the same expression, but if I change the number "2.9" to be some other numbers (roughly >3 or <2.8), then Maple "will" give me the answers. What happened? Can anyone tell me why Maple refuse to do the work during that range of value (roughly between 2.8 to 3). It's even weird. If you change the initial index of the sum from...

here mentioned:

275305224 is the third 91768409 gonal number.

can you tell me in which of these algorithms we will reach to number 91768409 ?

wiki :

as you know the number of solutions for order 3 to 5 magic squares is as follow : 
(not counting rotations and reflections)

order 3: 1 solution

order 4: 880 solutions

order 5: 275305224 solutions

higher order: unknown ...


in the first look at 880 , simply appeared it can constructed by
2x5x8x11 (every factor increased by 3)

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