Here i caluclated for 64 puzzle in this way
hex:-8000000000000000 
dec:-9223372036854775808     end dec:- 18446744073709551615
wif:-KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYvLz3frbdQvwtiEXdcN
1/4 dec:-11529215046068469760
1/4page:-90071992547409920
wif:-KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYy1aGkYHUQAHaMZgodk
half:- 13835058055282163712
wif:- KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qZ1gAVqDyKPMSmqu4gLM
3/4dec:- 16140901064495857664
wif:- KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qZ4LkiuufANZhDQQv7rU
end:-18446744073709551615
wif:-KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qZ71LwzbM1MmwA5Y2AFF
for puzzle 64 19 letter need to be permutate,
i divided the entire key space into 4 equal parts then calculated
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3q this is partilkey Yv, Yw,Yx,Yy,Yz, Z1,Z2,Z3,Z4,Z5,Z6,Z7 next seires where the 64 puzzle wif would be
thank you