/*** author: yuji9511 ***/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> lpair;
const ll MOD = 1e9+7;
const ll INF = 1e18;
#define rep(i,m,n) for(ll i=(m);i<(n);i++)
#define rrep(i,m,n) for(ll i=(m);i>=(n);i--)
#define printa(x,n) for(ll i=0;i<n;i++){cout<<(x[i])<<" \n"[i==n-1];};
void print() {}
template <class H,class... T>
void print(H&& h, T&&... t){cout<<h<<" \n"[sizeof...(t)==0];print(forward<T>(t)...);}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	ll Q;
	cin >> Q;
	while(Q--){
		ll N,K;
		cin >> N >> K;
		if(K == 1){
			print(N-1);
		}else{
			N -= 1;
			ll ans = 0;
			ll v = 1;
			while(N > 0){
				ans++;
				N -= v;
				v *= K;
			}
			print(ans);
		}
	}
	

}