Counting a Factorial Using Rust

factorial.rs

use std::io;

fn factorial(i: u64) -> u64 {
    let mut acc = 1;
    for num in 2..=i {
        acc *= num;
    }
    acc
}

fn main() {
    loop {
        println!("Input Number: ");

        let mut n = String::new();

        io::stdin().read_line(&mut n)
            .expect("Failed to read line");

        let n: u64 = match n.trim().parse() {
            Ok(num) => num,
            Err(_) => continue,
        };

        let answer: u64 = factorial(n);

        println!("Result is: {}", answer);
        break;
    }
}