fibonacci numbers

Accepted answer

Hello https://www.c-sharpcorner.com/members/ahmed-alngar,

It seems that result exceeds range of ULONG type :

Holds unsigned 64-bit (8-byte) integers ranging in value from 0 through 18,446,744,073,709,551,615 (more than 1.84 times 10 ^ 19).

So the only way to calculate F(2816213588) is to use Bigint type of variable to store result.

https://docs.microsoft.com/en-us/dotnet/api/system.numerics.biginteger?view=netframework-4.8

There are many good articles about Bigint on C# Corner :

https://www.c-sharpcorner.com/search.aspx?q=Biginteger

All the best,

Željko Peric

Use bigint instead of ulong

thanks a lot

Hi, Expecption is very clear due size is large and can't handled by ulong . So You have to use bigint datatype it will work.