use std::io::Read;

fn run() {
    let mut s = String::new();
    std::io::stdin().read_to_string(&mut s).unwrap();
    let mut it = s.trim().split_whitespace();
    let q: usize = it.next().unwrap().parse().unwrap();
    for _ in 0..q {
        let n: usize = it.next().unwrap().parse().unwrap();
        let k: usize = it.next().unwrap().parse().unwrap();
        if k == 1 {
            println!("{}", n - k);
            continue;
        }
        let mut sum = 1;
        let mut d = k;
        let mut ans = 0;
        while sum < n {
            ans += 1;
            sum += d;
            d *= k;
        }
        println!("{}", ans);
    }
}

fn main() {
    run();
}