Explanation
Both are approximate.
Dividing the two values will get us: 142984/12756 = 11.209156 approximately.
This means that if the scale model of Earth has diameter 1 cm on paper, then Jupiter will have a diameter of roughly 11.209156 cm. So it's about 11.21 cm depending how you round it.
Put another way: Jupiter's diameter is about 11 times larger compared to Earth's diameter. We can fit around 11 Earths stacked together side by side to fit inside Jupiter's diameter.