n=int(input())
import math
for r in range(n):
    a,b=(int(i) for i in input().split())
    l=[]
    for i in range(a,b):
        for j in range(2,int(math.sqrt(b)+1)):
            if i%j==0:
                break
        else:
            l.append(i)
    for i in range(b,2*b):
        for j in range(2,int(math.sqrt(2*b)+1)):
            if i%j==0:
                break
        else:
            l.append(i)
            break
    w=0
    for i in range(len(l)-1):
        s,d=str(l[i]),str(l[i+1])
        q=1
        u=0
        while(True):
            k=str(q)+s
            if int(k)%int(d)==0:
                u=int(k)
                break
            q+=1
        w+=u
    print(w)