Relation of Avogadro's number to mole:

One mole of hydrogen atoms = 6.02 x 10²³ atoms of hydrogen (H) = 1 a.m.u

One more of hydrogen molecules = 6.02 x 10²³ molecules of hydrogen (H₂) = 2 a.m.u

One mole of water = 6.02 x 10²³ molecules of water (H₂O) = 18 a.m.u

$\text{Number of moles of a substance} = \frac{\text{Number of molecules of a substance}}{N_{A}}$

$\text{Number of moles of a substance} = \frac{\text{Number of molecules of a substance}}{6.02 \times 10^{23}}$