We may be speaking across each other here. Ruby is lying in the sense that there are multiple distinct float values that it will print as 0.3 – in particular, confusion ensues when two values look the same but are unequal. These other languages print each distinct float value differently, using just enough decimal digits to reconstruct the exact binary value. Ruby doesn't give you enough digits to reconstruct the value you have. Nobody actually prints the full correct value because it's fifty digits long and is completely redundant given that you know you're dealing with a 64-bit float.