Hex, or hexadecimal, is a number system of base 16, using the first 10 digits (0,1,2....9) and the first 6 letters of the English alphabet.
Hexadecimal=Decimal
0 0
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
A 10
B 11
C 12
D 13
E 14
F 15

You can perform Hex -> decimal conversion by using Omniscope operations - Expand values, Search/Replace and formulas.

IF(
[Class]=1,[Value]*POWER(16, 0),
[Class]=2,[Value]*POWER(16, 1)+[Value (1)]*POWER(16, 0),
[Class]=3,[Value]*POWER(16, 2)+[Value (1)]*POWER(16, 1)+[Value (2)]*POWER(16, 0),
[Class]=4,[Value]*POWER(16, 3)+[Value (1)]*POWER(16, 2)+[Value (2)]*POWER(16, 1)+[Value (3)]*POWER(16,0)
,
null)


Please see attached file that you can use as a template, replacing the original data source with your own.

You can also use a formula field using the script function to achieve this:

SCRIPT('parseInt(valueToConvert, 16)', "valueToConvert", REFVAL("Hex"), 10000)


Where "Hex" is the field which contains hex value (Example attached).