Convert picometer to megameter

Atoms and molecules are measured in ångströms, 0.1 nm: the Bohr radius of hydrogen is 0.53 Å, a carbon–carbon bond 1.54 Å, and X-rays have wavelengths of about 1 Å, which is why crystallographers keep the unit although it is not part of the SI (chemistry tables give the same radii in picometres, 53 pm). The nanometre is the scale of the DNA double helix (2 nm across), of viruses (20–300 nm) and of visible light (380–750 nm); a chip's '3 nm' process is a marketing name, its transistors are really tens of nanometres apart. Bacteria, red blood cells (7 µm) and hair (50–100 µm) belong to the micrometre, and the femtometre, or fermi, to the atomic nucleus: a proton is 1.7 fm across.