Related Clues:

• Make a summation?
• Tally up
• Use a plus sign
• Mention as an afterthought
• Calculate sums
• Do some simple calculating
• Do a summer's work?
• Compute, sometimes
• Write, as a P.S.
• Offer as a bonus
• Make a contribution
• Write in a postscript, e.g.
• Use a '+'
• Calculate the total
• Cookbook directive