Hexadecimal Variables???????

I have inside of string a hexadecimal value:

strHexa="045f456678eddfeadfe345629000a1001010e............

Its long is nerly to 4090 characters. This string update a hexadecimal fields in a table. When I need update this field using this string, its is converted in other value, of course, its is a string and not hexadecimal value. In the update moment this makes a converts to hexadecimal value. If I try convert this string to decimal, when had pass 200 characters occurs a overflow error, using a double, its value is over 1.79.....E+308. I think that using a Hexadecimal Variable, the update do not make a convert, and take this value, inside of the variable as hexadecimal value to upate.
Please. Are there some way to declarate a hexadecimal value. Or to converts from too long or bigger Hexadecimal to decimal value????
Thanks to all!!!!!!!!!!1
Bye
Juan Carlos Chacón

There must be a better way to do whatever you really want to do.

Huge Hexidecimal values can be converted to huge Decimal values and vice versa. It requires the programming of Extra Precision arithmetic.

Except for weird applications (calculate Pi to thousands of digits, for example), there is seldom a real need for processing huge numbers or values with thousands of digits.

I suspect that further analysis of your application would lead to some easier method than what you are trying to apply.