Crossword puzzle clue "one and one together"

Put together together

"Love and marriage, love and marriage, go together like a horse and carriage," e.g.?

One and one together?

Puts one and one together?

Add vertical line 13 (word 3) and vertical line 3 (word 1) together and enter the answer to the resulting clue on this line

Can the whiz with the sketchpad put two and two together and ___?

One putting two and two together

Person who puts one and two together?