The printing routine. Internally, none of them can store 0.3 in a floating point variable because it is impossible to do so in exponential notation with base 2

The printing routine. Internally, none of them can store 0.3 in a floating point variable because it is impossible to do so in exponential notation with base 2 (which is what IEE 754 uses). Some languages may optionally use an exact representation (e.g., Scheme or Python), but that's not the general case.