#include <bits/stdc++.h> #define setIO(s) freopen(s".in","r",stdin) #define ll long long #define maxn 100000 using namespace std; int arr[30],brr[maxn]; ll calc(ll t) { int n=0,m=0; while(t) arr[++n]=t%10,t/=10; while(n>=1) { for(int i=2;i<=n;++i) brr[++m]=(arr[i]+arr[i-1])%10; while(brr[m]==0 && m>=2) --m; for(int i=1;i<=m;++i) arr[i]=brr[i]; n=m,m=0; } return arr[1]; } ll solve(ll k) { if(k<10) return k*(k+1)/2; ll re=(k/10)*45,t=calc((k/10)*10); int o=k%10; for(int i=0;i<=o;++i) re+=1ll*(t+i)%10; return re; } int main() { // setIO("input"); int T; scanf("%d",&T); while(T--) { ll l,r; scanf("%lld%lld",&l,&r); printf("%lld\n",solve(r) - solve(l-1)); } return 0; }
