Related Clues:

• Stirs in
• Does arithmetic
• Tosses into the mix
• Finds 23-Down
• Puts in the mix
• Gets to the bottom of things?
• Interjects
• Sums up?
• Postfixes, e.g.
• Determines a sum
• Throws on
• Puts two and two together?
• Tosses in
• Uses postscripts
• Computes columns