TRUE BUT DEPEND ON HOW MAN GPU
 The total number of keys
From:  0x4000000000000000 =  4,611,686,018,427,387,904
To:    0x5000000000000000 =  5,768,357,523,034,234,880
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Diff:  0x1000000000000000 =  1,152,921,504,606,846,976 keys  if im not wrong 5.55 hours using 20 gpu   please correct me??