import sys

sys.set_int_max_str_digits(100000)
t = int(input())
inf = int(int(1e5) * '1')

for tt in range(t):
    n, k = map(int, input().split())
    s = input()
    len = n // (k + 1)
    r = n - len * (k + 1)

    ans = 0
    cur = 0

    if n % (k + 1) == 0:
        len = n // (k + 1)
        while cur < n:
            ans += int(s[cur : cur + len])
            # print(cur, cur + len, s[cur : cur + len])
            cur += len
        print(ans)
        continue

    ans = inf
    # print(len, r)
    for j in range(k + 1):
        cnt = 0
        temp = 0
        cur = 0
        while cur < n:
            if cnt == j:
                temp += int(s[cur : cur + r])
                cur += r
            else:
                temp += int(s[cur : cur + len])
                cur += len
            cnt += 1
        ans = min(ans, temp)

    print(ans)