SPOJ Digit Sum

#include <iostream>


#include <cstdio>


#include <cstring>


#include <map>


#include <string>


#include <vector>


#include <cmath>


#include <cctype>


#include <sstream>


#include <set>


#include <list>


#include <stack>


#include <queue>


#include <algorithm>


#define sf scanf


#define pf printf


#define sfint scanf ("%d %d",&a,&b)


#define sfl scanf ("%ld %ld",&a,&b)


#define sfll scanf ("%lld %lld",&a,&b)


#define sfd scanf ("%lf %lf",&a,&b)


#define sff scanf ("%f %f",&a,&b)


#define loop(i,n) for(i=0;i<n;i++)


#define LL long long


#define L long


#define nl puts("")


#define MX 1000005


#define N 100


#define MOD 10000000007


#define pb push_back


#define pi acos(-1.0)


#define sz size()


#define gc getchar ()


#define ps push


#define clr clear


#define bn begin()


#define ed end()


 


using namespace std;


 


/*int sumofDigit(int N)


{


if(N<10)


return N*(N+1)/2;


int n=N,i;


while(n/10!=0)


{


i++;


n/=10;


}


int p=pow(10,i);


return ((n*i*45*p/10)+(n*(n-1)*p/2)+n*(N%p+1)+sumofDigit(N%p));


}*/


 


LL digit(LL n)


{


    if (n<10) return n*(n+1)/2;


 


    LL take=n,i=0;


    while(n/10 != 0)


    {


        i++;


        n/=10;


    }


 


    LL p=pow(10,i);


    return ((n*i*45*p/10) + (n*(n-1)*p/2) + n*(take%p+1) + digit(take%p));


}


int main()


{


    LL x,y,t; cin >> t;


    while(t--)


    {


        cin >> x >> y;


        cout << digit(y) - digit(x-1); nl;


    }


 


    return 0;


}