What is the largest denormalized float value? We need

      s    = 0
      e    = 0
      frac = 0x7fffff (23 1's; only 23 bits, drop first 0)
   

Note f is 2²³ - 1 as an integer, but we must divide this by 2²³ to get the fractional part.

      f = frac / 223 = 1 - 2-23 = 1 - ε
      M = f (for denormalized floats)
   

The value, V, of this float is

      V = (-1)s 2Exp M
        = (-1)s 21 - 127 (1 - ε)
      = 2-126 (1 - ε)

      Note: ε = 2-23 = 0.00000012 (to 8 decimal places)
            (1 - ε) = 0.99999988