Question: If there are 2 number system, e.g. Decimal Number System with 10 symbols (0-9) and hexadecimal with 16 Symbols (0-9,A-F), can i conclude that with hexadecimal, i will be able to retain greater accuracy than with the decimal number system due to the higher number of symbols ??

Edit1:
Sorry, i was asking only from the point of view of a computer, it may be for a written calculation or anything

Answer: 
Accuracy is related to non-integer (real) numbers. It depends on 

1. Radix (decimal, hex)
2. Amount of digits

For same amount of digits hex can be more accurate.

Simplest example: Radix: decimal and binary. Amount of digits: 1.

In case of decimal you can have from `0.0` to `0.9`, in case of binary only `0.0` to `0.1` (`0.5` in dec). Decimal is 5 times more accurate.
You cannot say anything about accuracy unless you know what you are trying to represent.

For example, if you are trying to represent things measured in hundredths, e.g., pennies, decimal is more accurate than hex for the same number of digits (2). You cannot represent 0.10 exactly in hex (or binary), but you can in decimal.

See the [General Decimal Arithmetic](http://speleotrove.com/decimal/) web page for more details.