XICalc is a freeware integer calculator program with the following features: • Multiple precision integers with millions of digits • Uses Fast Hartley Transform to speed-up long multiplies • Uses Binary Splitting to speed-up computing factorials • Separate input and output notation, base 2 to base 36 • Greatest Common Divisor function • Modulo arithmetic options • Bernoulli numbers, Euler Numbers • Boolean functions • Random number generator • Prime factor algorithm using the Elliptic Curve Method • Number theoretic functions Phi, Sigma and Tau • Prime testing and searching using the Adleman function • Algebraic notation (not reverse polish) • If-then-else statement • Goto statement • Can run XICalc code from files • Hot Help from F1 key • Written in Microsoft Visual C# .NET 2003 for Windows • and more ... . All C# source files and documentation included Requires Microsoft .NET Framework 1.1.