How does an atom become a positively charged ion?

An atom has an equal number of protons (+ charged) and electrons (- charged). When an atom loses an electron or 2, it has more protons than electrons, and so more positive charges than negative. Then the atom is called a positive ion. The atom that took the electron or 2 became a negatively charged ion. The 2 atoms are likely to be attracted to each other because of their opposite charges; they stick together and form an ionic bond.

Yes you are correct use the scientific method

60.0 - there are 3 significant numbers