#include<bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int Q;
  cin>>Q;
  while(Q--){
    int a,b;
    cin>>a>>b;
    if(b==1){
      cout<<a-b<<endl;
    }
    else{
      int ans=0,memo=1;
      while(memo<a){
        ans++;
        memo*=b;
      }
      cout<<ans<<endl;
    }
  }
}