/*
This program computes the factorial of numbers greater than 20.
Scala's BigInt type automatically expands to arbitrary size,
making it ideal for very large factorials.
*/
/*
Compute factorial using BigInt.
The algorithm multiplies numbers from 2 to n.
BigInt handles overflow internally and grows as needed.
*/
def factorialBig(n: BigInt): BigInt = {
var result: BigInt = BigInt(1)
for (i <- BigInt(2) to n) {
result *= i
}
result
}
/*
Main entry point: read input, compute factorial, print result.
*/
object BigFactorial extends App {
print("Enter a number greater than 20: ")
val n: BigInt = BigInt(scala.io.StdIn.readLine().trim)
val result: BigInt = factorialBig(n)
println(s"\nFactorial of $n is:\n")
println(result)
}
/*
run:
Enter a number greater than 20: 25
Factorial of 25 is:
15511210043330985984000000
*/
