fn is_armstrong_number(num: u32) -> bool {
    let num_digits = (num as f64).log10().ceil() as u32;
    let mut remainder = num;
    let mut armstrong_sum = 0;
    for power in (0..num_digits).rev() {
        let power10 = 10u32.pow(power);
        let digit = remainder / power10;
        remainder -= digit * power10;
        armstrong_sum += digit.pow(num_digits);
    }

    num == armstrong_sum
}

fn main() {
    println!("{}", is_armstrong_number(9));
    println!("{}", is_armstrong_number(153));
    println!("{}", is_armstrong_number(154));
}