t = input()
while not t.strip():
  t = input()
t = int(t)
for _ in range(t):
  line = input()
  while not line.strip():
    line = input()
  n, k = map(int, line.split())
  s = input()
  while not s.strip():
    s = input()
  k = min(n, k + 1)
  same, extra = n // k, n % k
  ans = int(s)
  for mask in range(0, 1 << k):
    if bin(mask).count('1') != extra:
      continue
    sizes = [same] * k
    for i in range(0, k):
      if mask & 1 << i:
        sizes[i] += 1
    at, total = 0, 0
    for l in sizes:
      total += int(s[at : at + l])
      at += l
    ans = min(ans, total)
  print(ans)