Related Clues:

• 8, for oxygen: Abbr.
• __ cost (free)
• 12 for Mg or 20 for Ca, e.g.
• Bit of elementary knowledge?: Abbr.
• "... __ additional cost to you!"
• ___ badge
• -- additional cost
• -- cost (on the house)
• "... ___ cost to you"
• Chem class abbr.
• Elementary figure: Abbr.
• 1.008, for hydrogen: abbr.
• No. on a periodic table
• Periodical table abbr.
• 4 for He, e.g.