C++ :

#include<bits/stdc++.h>
using namespace std;
long long q,a,b,ans;
int f(long long x)
{
	while(x>=10)
	{
		int tmp=0;
		for(long long i=x;i>0;i/=10)
			tmp+=i%10;
		x=tmp;
	} 
	return x;
}  
int main()
{
	cin>>q;
	while(q--)
	{
		cin>>a>>b;
		long long lun=(b-a+1)/9;
		long long yu=(b-a+1)%9;
		ans=45*lun;
		for(int i=f(a),j=1;j<=yu;i++,j++)
		{
			if(i==10) i=1;
			ans+=i;
		}	
		cout<<ans<<endl;	
	}	

    return 0;
}