Related Clues:

• "Duh ... figure it out!"
• To gain a section
• Do very easy math
• Tack on, as tax
• ___ line (dipstick mark)
• Use a 112-Down
• Verb in a recipe
• Sum, put together
• Throw in sample of bread dough
• Use the "=SUM" function, say
• Tack on song to iPod
• Do some arithmetic
• ''. . . above our poor power to __ or detract'': Gettysburg Address
• Opposite of subtract
• Put numbers together