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# Octal and Hex

L Sol
Greenhorn
Posts: 3
I am a bit confused on how to calculate these Octal and Hex numbers for the exam. Do we even need to be able to calculate these? Thanks!

Nathaniel Stoddard
Ranch Hand
Posts: 1258
I'm not sure if there are problems that explicitly ask you to compute the decimal value of a given hex value, but the understanding how to do so may help you out.
To find the decimal value of some hex or octal, just multiple each digit by the base and placement:
FA1 = 15 * (16 ^ 2) + 10 * (16 ^ 1) + 1 * (16 ^ 0)
Octals would be the same way except the base would be 8 instead of 16. Binary likewise except the base is 2. And so on.
The exam objectives include the use of Integer.toHexString(int), so I would say this is definitely a good thing that you're asking this.
[ March 23, 2004: Message edited by: Nathaniel Stoddard ]

L Sol
Greenhorn
Posts: 3
I apologize, I think I am still missing something. What you said makes sense to me... but when I calculate FA1 out I get that it is equivalent to 641. When I use my scientific calculator and type in FA1 and convert it to Decimal. It tells me 4001. What am I missing?