import java.math.BigInteger
/*
This program computes the factorial of numbers greater than 20.
Kotlin uses Java's BigInteger for arbitrary‑precision arithmetic,
allowing us to safely compute extremely large factorials.
*/
/*
Compute factorial using BigInteger.
The algorithm multiplies numbers from 2 to n.
BigInteger handles overflow internally and grows as needed.
*/
fun factorialBig(n: Int): BigInteger {
var result: BigInteger = BigInteger.ONE
for (i in 2..n) {
result = result.multiply(BigInteger.valueOf(i.toLong()))
}
return result
}
/*
Main entry point: read input, compute factorial, print result.
*/
fun main() {
print("Enter a number greater than 20: ")
val n: Int = readLine()?.trim()?.toIntOrNull() ?: 0
val result: BigInteger = factorialBig(n)
println("\nFactorial of $n is:\n")
println(result)
}
/*
run:
Enter a number greater than 20: 25
Factorial of 25 is:
15511210043330985984000000
*/
