On what floor of the White House does the president and his family live?

The First Family lives on the 2nd and 3rd floors. The only place they can go without the Secret Service. When the President is out of the country the flag is not flown at the White House. Again refer to the Explorer special.

The President, the President's family, their guests, and the President's staff use many other rooms in the White House every day. The ground floor contains the Diplomatic Reception Room, used as the entrance for formal functions; the kitchen; the library; and offices of the White House physician and curator.

The second floor contains the living quarters of the President and the President's family. The Lincoln Bedroom, the Treaty Room, and the Queen's Room are also on that floor. The third floor contains guest rooms and staff quarters. The White House also has a private bowling alley, swimming pool, and movie theater.

https://en.m.wikipedia.org/wiki/Executive_Residence

The third floor also has the solarium, used by several First Families as an informal living room. The Treaty room on the second floor was turned into the President's private office under Clinton. Along with the state rooms, the first floor also has the Private Dining Room, used frequently for smaller official meals. The bowling alley, which hasn’t been used since 9/11, and theatre are in the basement. The indoor pool, built for Franklin Roosevelt and decorated with a mural of Hyannisport for Kennedy, was filled in for a press room under Nixon. The outdoor pool was built for Gerald Ford and recently refurbished for George W. (at a cost of $430,000).
The White House is also one of the few American houses to have the more European designations Ground, First and Second floors, rather than First, Second and Third.