D:\>perl -MDevel::Peek -le "$x = (2 ** 53) - 1; Dump $x; $x++; Dump $x; $x++; Dump $x; $x++; Dump $x;"
SV = NV(0x28e88c5a2f8) at 0x28e88c5a310
  REFCNT = 1
  FLAGS = (NOK,pNOK)
  NV = 9007199254740991
SV = PVNV(0x28e88c24e10) at 0x28e88c5a310
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 9007199254740992
  NV = 9007199254740991
  PV = 0
SV = PVNV(0x28e88c24e10) at 0x28e88c5a310
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 9007199254740993
  NV = 9007199254740991
  PV = 0
SV = PVNV(0x28e88c24e10) at 0x28e88c5a310
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 9007199254740994
  NV = 9007199254740991
  PV = 0