double three = 3.0; double point3 = 0.3;What can we say about the stored values?

Integers are represented exactly in floating point, up to the limits of
the mantissa accuracy (about 15 digits for `double`).

Decimal fractions usually cannot be represented exactly in binary. Just as 1/3 = .3333333... in decimal, 1/10 is an infinitely repeating pattern in binary. Therefore, any floating-point number with nonzero digits after the decimal is probably represented as an approximation in binary.

Floating point representation is governed by an IEEE Standard, which all CPU chips follow. Therefore, the representation of a floating-point value will be the same no matter which CPU chip is used.