The Clue Does 987.654321 + 1234.56789, say
The Answer ADDS
The clue "Does 987.654321 + 1234.56789, say" refers to a mathematical operation. When you add two numbers together, you are performing the action of "adding." The word "adds" fits perfectly as it describes what is happening in the equation. Therefore, the answer to the crossword clue is "ADDS."