What is the best base to use? When I typed this question in google I found this link: http://octomatics.org/ Just from the graphic point of view: this system seems to be easier (when he explains that you can overlap the line). He also talks about how base 8 is useful for computers. Is base 8 really the best,what makes one base better than the other. Is there some mathematical argument that we can use to decide which is the best base to use? Thank you for your insight, I think the answer has to be entangled with other areas of knowledge as cognitive sciences or simply how large are the numbers that are used more often but: Arithmetic is something that almost everybody does so it is probably worth a while to try to see if we are making it as easy as possible. Thank you very much in advance.
 A: We could say that there are two desirable goals for a base system:


*

*A minimized number of symbols (e.g. there are two symbols in binary, 0 and 1).

*Minimal digital lengths for each number (e.g. the number 10101 has a length of 5 digits in binary).


Let us say our base is $b$, and hence we have exactly $b$ symbols to represent numbers with.  The digital length of a number is then represented as $\log_bN$ for a positive number $N.$
There are many ways to attempt to minimize both of these values simultaneously.  One way is to minimize $||\langle b,\space \log_bN \rangle||_p$, where $||\small \vec x||_p$ is the p-norm of $\vec x$, and where $N$ can be any arbitrary number (hence $N$ becomes a weighting parameter of sorts).
The results you obtain with the above algorithm are completely dependent on what values you choose for $N$ and $p$.  So while there is no absolute answer, you can obtain one by assigning fixed values to these two parameters.
A: To have the largest readership possible, along with the greatest probability of your readers reading your work until the end, and the probability of your readers also finding your work easy to read, at present, it seems you want base ten.
There doesn't exist any mathematical argument as to which base system comes as the best until we have criteria to determine what "the best" would mean.  Who do we want to talk to?  For what purpose do we talk to them?  What sort of background do they have?  What sort of tools do they have?  What can those tools do?  
A: It depends what you find 'best'. Personally I don't care whether it's easy to convert to binary, since computers do that just fine for any base, so I never need to.
What is a little bit more annoying for humans is fractions that don't terminate. So I think to get the best base, you just multiply prime numbers from low to high until you feel the base gets too big. E.g.
1 * 2 = 2
1 * 2 * 3 = 6
1 * 2 * 3 * 5 = 30
1 * 2 * 3 * 5 * 7 = 210
....

Using base 30, fractions like 1/2, 1/3, 1/5, 1/6, 1/8, 1/9, 1/10 or 1/15 factorizes nicely because the denominator's prime factors are also prime factors of your base. In that respect, base 12, or any $2^N$ base, waste numbers because they have double prime factors. The same fractions that terminate in base 12 also terminate in base 6.
Base 210 is definitely too big since you need to remember like 21.000 multiplications. Base 30  isn't really fun at around 400 either, but that's doable. The best bet may be 6. A quarter is not ideal though (3/20).
A: Base 3 is optimal b/c it can be shown to be the most efficient means of information storage as a balance between the number of symbols and the space they take up. Wish I had the paper handy that provides the proof of this so I can reference it. Unfortunately it is buried in some boxes. But it does exist and the reason has to do with the natural log (technically the natural log is the most efficient, but a fractional base, while possible, is obviously not practical). 
However, that doesn't make base 3 best for humans b/c we are, obviously, not simple calculating machines. For us, we have to take pattern recognition and memory into account. Which means an effective base has to strike a balance between our ability to recall a long number of a few symbols and are ability to manipulate a short number of many symbols. Which, to get to the point, means it must lie somewhere between 4 and 16. Also, odd numbers are out b/c dividing by two evenly is a practical necessity. Beyond that we have to consider other practical aspects.
Both 4 and 16 push the limits of practical everyday use. Base 4 is very long winded, and 16 requires too much table memorization. While base 16 has utility for working with computers, that is really the only reason for it's use. Although, to its credit, it is the most concise. Base 8 is much more practical for every day usage while still being useful for computer work. Issac Asimov was a big proponent of using base 8 instead of base 10.
In contrast many people think base 12 is better because is has the most divisors: 2,3,4 and 6. This makes it very convenient for working with the division of things. Dividing a base 12 number by any of these is as easy as dividing a base 10 number by 5. On the downside, base 12 still has a somewhat large times table to memorize. Avoiding that leads us to base 6 (also known as senary), which has a trivial times table and yet has most of the division benefits of base 12. Though it can't be divided by 4 evenly, base 6 numbers can be taken in pairs and evenly divided by 4 and 9, which easily makes up for the deficiency. Another cool aspect of base 6 is that it can be counted on one's hands as easily as decimal. Each hand simply represents a units place 0 to 5, allowing a person to count from 0 to 35.
In summary, while there is some subjectivity involved is designating one base as better than another, there are some clear criteria that limit the selection to only a handful of possible values. 
A: A while back I tried doing some pencil-and-paper arithmetic in base 16 (extraction of square roots) to see what it was like, and found that it was hard mainly because I don't have the base-16 multiplication table memorized, and there is a lot to memorize. My conclusion at the end was that the easiest way to do base-16 arithmetic is to do it in base 4 and then convert at the end; the conversion is trivial.  All the numerals have twice as many digits, but it takes much less than half as long to calculate each digit, so it is much faster. Converting to base 2 goes too far and loses the tradeoff; now the numerals are twice as long again, but you do not gain enough speed to make it worth while.
For base $n$, you have to memorize $\frac12\bigl(n^2-3n+2\bigr)$ multiplication table entries, since $0\times n$ and $1\times n$ are trivial, and $m\times n = n\times m$.  This increases rapidly with $n$: in base 10 you have 36 products to memorize; in base 16 there are 105. For base 4, you only have to remember $2\times 2 = 10, 2\times 3 = 12, $ and $3\times 3 = 21$.
I did not try any of the usual methods for speeding up paper-and-pencil multiplication, such as Napier's bones, or Genaille-Lucas rulers. But I don't think these would help enough. If you don't have the multiplication tables down pat, you lose a lot of number sense that you probably take for granted.  For example, you can't estimate the answer to division problems. The square root algorithm requires that you guess the answer to a lot of sub-problems of the type "How many times does 2D,409 go into 1C0,000?" and whereas this sort of thing is easy in base 10 because you have years of practice (What's $1,835,000\div 185,353$ to one decimal place?) it is hard in base 16. So knowing the multiplication tables is important, and in base 16 there is a lot to know.
I found the exercise very enlightening, and I recommend it. If nothing else, it may be interesting to re-experience feelings that you have not had since third grade.
Converting to and from base 8 is not so felicitous, but the multiplication table is not too hard to memorize. Still I think the advantage over bases 4 or 16 are minimal, if they exist at all. I think the worst choice for pencil calculation would be a large prime number, since there's no easy conversion to a smaller base as there is from bases 8 or 16 to base 4.
The desiderata for computer calculation are of course completely different, and for abacus calculation are different again. For computers I have seen claims that base 3 is in some sense optimal, but I think 70 years of engineering practice refutes that completely. There is a certain sense in which modern computers operate not in base 2 but in base 256, but it seems to be something of a philosophical question which it is; it depends on what level of operation you are looking at. 
A: Base 8 has direct conversion back and forth binary and would work almost equally well. 
Having base-2 rather than anything else is a matter of electronics/hardware concerns 
before even getting into the values-in-any-base zone. Each separate bit is converted 
from an analog stream to binary through a measure it is judged-- it is cast as 1 if it 
is closer to 1 than it is to 0 and vice verse (An electronics expert would comment further on this). Splitting a signal among more choices would decrease 
its accuracy and is heavier on the hardware costs. The hardware was more expansive than the software on 
it back in the early days while these were all being set. 
A: Well there is some subjectivity, the larger the Base, the larger the times table. base 16 (hexadecimal) is awesome because it can be divided in half 4 times, making it great for computer work. however, base 12 is great because it has more divisors than any other 'small' base (1,2,3,4,6,12) which makes division very easy. Base 8 or base 6 have some (but not all) of the advantages of base 16 and 12 (respectively) but are smaller (half) and therefore have an easier times table to memorise. What can be agreed however, is that base 10 is not a great choice, as it has relatively few divisors, (1,2,5,10) and you end up with very awkward decimals of 3 and 4 (i.e. .33333 and .25). 
basically, we can't agree on what the best choice would be, but if we had it to do over again we wouldn't choose 10, and we would probably choose 6,8,12,or 16 as a base.
