Dot in chemical formula

[David Zhang 1B]

What does a dot in a chemical formula mean such as in problem E.23 when it asks about Na2CO3 (dot) 10H2O?

[Leah farhadi 1F]

I think that it means that there is 10 moles of H2O molecules in the compound. I think it is written this way as to not get confused with putting it in front of the chemical equation of the compound, as it makes it seem like there are 10 moles of the compound. Also, it helps to not get it confused with putting it as a subscript, as it can only be related to either H or O and not together as a compound (H2O).

[Chem_Mod]

Any chemical formula that has a dot and H20 is a hydrate, a substance that contains water.