Creating uber large numbers

[CryoEnix]

I'm currently writing a program that needs to calculate some very large numbers, the highest of which is (36 ^ 35). Although VB.NET can calculate this, the only variable it will fit in is a double, which always results in those horrid floating point numbers. Is there any way I can get an exact number for the answer in VB, for example by using a custom made (albeit massive) variable?

[IngisKahn]

Wow, that is a big large number.

Just wondering what you need 55 digits for.

And ya, you'd probably be best off with a structure consisting of a couple Decimals.

[CryoEnix]

Wow, that is a big large number.

Just wondering what you need 55 digits for.

 

The program is to dynamically create a keygen generator for my programs, to save doing it by hand each time - I just need to enter details such as whether I want it to be alphanumeric, numeric etc, how often the dashes are ("-") and how many chars long it is. The large number is for previewing the generated keygen, so I can see the possible combinations and the odds of someone guessing a correct serial.

I'm trying to write a module that will return the result in a string form, but if one's already been written I feel it's better to ask than reinvent the wheel.

[CryoEnix]

Erm, I've written the module now, but how the hell did you know it was 55 digits long? What's that algorithm? :eek:

[Cags]

And your module is actually working? Isn't double only accurate to about 15 decimal places?

[IngisKahn]

36^35 is 55 digits (2.955e54). :)

 

All you're concerned about is the string? If so, then why use large numbers at all?

[CryoEnix]

36^35 is 55 digits (2.955e54). :)

 

All you're concerned about is the string? If so, then why use large numbers at all?

 

Nonono, the module just returns the number as a string, to make its manipulation easier. I've managed to calculate 36 ^ 35 to:

 

2955204414547681244658707659790455381671329323051646976

 

I was surprised as to how fast VB actually calculated it - it's come a long way since VB6...

 

Cags - I'm not sure when it comes to doubles, and I only needed the module to calculate whole numbers. The module works by breaking up the result into a manageable array before reassembling it as a string value - the answer can be a large as 32767 digits!

[IngisKahn]

Heh, a bit overkill no?

If you were to count every atom in the universe you'd only need 80 digits.

[mskeel]

the answer can be a large as 32767 digits!

If you were to count every atom in the universe you'd only need 80 digits.

I laughed so hard when I read that! That is awesome!

[CryoEnix]

Lol! That's pretty cool, the whole universe thing. Well, I'm off to finish the program with a nice 'Uber large Division' algorithm. Just hope I don't have to deal with many decimals...