Rule 23(a) requires a finding that the numerosity of injured persons makes joinder of all class members “impracticable.” Robidoux v. Celani, 987 F.2d 931, 935 (2d Cir.1993). Impracticable does not mean impossible, but simply difficult or inconvenient. See id.; Reynolds v. Giuliani, 118 F.Supp.2d 352, 388 (S.D.N.Y.2000). “There is no magic minimum number that will breathe life into a class,” Jones v. CCH-LIS Legal Information Servs., 1998 WL 671446, *1 (S.D.N.Y. Sept.28, 1998), but generally, courts will find a class sufficiently numerous when it comprises forty or more members. Robidoux, 987 F.2d at 936; Martin v. Shell Oil, 198 F.R.D. 580, 590 (D.Conn.2000). However, an estimate that is based on speculation is insufficient. See Deflumer v. Overton, 176 F.R.D. 55, 58-59 (N.D.N.Y.1997) (<HOLDING>); see also Demarco v. Edens, 390 F.2d 836, 845
holding that mere conjecture or speculation is insufficient under a preponderance standard holding that mere speculation is insufficient to support a jury verdict holding that mere speculation does not satisfy the nonmoving partys burden of establishing a dispute of material fact sufficient to defeat a motion for summary judgment holding that pure speculation  is insufficient to satisfy movants burden holding speculation insufficient to avoid summary judgment