In a family supper, a grandfather, a grandmother, two fathers, two mothers, four children, three grandchildren, one brother, two sisters, two sons, two daughters, one daughter in law, and one mother in law need to sit at a table.

There are only seven chairs available at the place. How many more chairs do they have to borrow so that everyone can sit down together for the suppers if everybody requires a separate chair?

HubSpot Interview Puzzle

No other chair is required as there are only seven people:
A Grandfather married to Grandmother.
They have a son who is married to a woman.
Together, they have three children - One son and two daughters.

These are the only seven people

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