def f(s):
 while len(s)>1:
  t=[0 for _ in xrange(len(s))]
  for i in xrange(len(t)-1):
   t[i]=s[i]+s[i+1]
   if t[i]>9:
    t[ i]=t[i]%10+1
  s=t[:-1]
 return s[0]
 
n=int(raw_input())
for i in xrange(n):
 s=map(int,raw_input())
 print f(s)