How do you figure out alphanumerics?

Answer 1

if you are talking about the more general CS term of alphanumerics, then you are talking about all printable characters such as all letters, numbers, symbols, punctuation marks, etc. So, if your question is what are alphanumerics, there you go.

Now, if you want to know about hexadecimal, then look at it this way. What we use for our numbering system is base 10 and, thus, the reason that it is called Decimal. Deci- is a prefix meaning ten, after all. Hexadecimal is a combination of the two prefixes Hex- and Deci-. In this case, they are to represent six plus ten or, in other words, base 16. Now since there are only ten numerals in our numbering system, we had to borrow some letters to stand in for the additional numbers, specifically A through F.

So, how does hexadecimal work? It works just like decimal: you can have up to the base number minus one as the maximum value for each place. So, for the ones place, you can have values 0 through 9. The same with the next place, which is called the tens. So, the number 63 means 6 in the tens place and 3 in the ones place. In hexadecimal, the same pattern holds true but the maximum value increases. The minimum of course is still zero but the top value is F. So, if you want to see how it works, let's use the hexadecimal value of 3F. This means that there is a 3 in the sixteens place (it is sixteens because this is hexadecimal, so a base 16 numbering system) and F in the ones place.

Now, you might want to try to figure out how to convert from hexadecimal to decimal. Well, it's very simple. Since we know that 3F is 3 sixteens and F ones, we can do a bit of easy multiplying. 3 x 16 is 48 and F is the maximum value that can be in a place in base 16, so as the rule said, that must mean that it is the base value minus 1, which is 15. So, 3F is 48 plus 15, or 63. (Hmmm, interesting how that worked out, huh? ;-) )

Now, what about larger values? The same pattern continues. In decimal, the places are singles, tens, hundreds, thousands, etc. Each time we move a place to the left, the value increases by a factor of ten. Basic, right? Well, the same pattern holds true for hexadecimal but it instead increases by a factor of sixteen. Thus, you have singles, sixteens, 256s, 4096s, etc. So, to show how it works, let's try 3F0. This means that we have 3 in the 256s place, F in the 16s place, and 0 in the singles. Once again, we do a bit of multiplication. 3 x 256 is 768, and F x 16 equals 240, so 3F0 is 768 plus 240, or 1008.

If you want to convert from decimal to hexadecimal, it is a bit more complex since most people don't think that way but it still isn't difficult. Let's convert 1008 back to hexadecimal. So we know that we have 1 in the thousands, 0 in both the hundreds and tens, and 8 in the singles. Well, we know that the maximum place with which we will be working is the 256s since the next step up is the 4096s. So, we are certain this will be a three-digit number. So, to start, how close to 1008 can we come with multiples of 256 without going over? That would be 3 256s, leaving a remainder value of 240 (in decimal, of course). So, we move to the next place: the 16s. How many multiples of 16 can we get out of 240 without going over? That is fifteen but we cannot write it as 15 of course, because that is decimal notation. In hexidecimal, that value is written as F. Since there is no remainder from that solution, we know that the singles value has a 0 in its place. Thus, the conversion of 1008 in decimal is 3F0 in hexadecimal.

Does this help you with either interpretation of your question? If you have any other questions or if this is about as clear as mud at midnight, let me know and I will be glad to assist you further.

Answer 2

The alphanumerics are called Hexadecimal numbering system. This and binary numbering system is what is used in the computer for device addresses.