Chicago Cubs First-Place Eliminiation Scenario
Chicago must win 27 more games (27 total) to avoid elimination from first place.
Here are the final standings in a scenario in which Chicago finishes in first place with 27 wins:

Team             W	L	PCT	GB
Chicago          27	135	0.167	0.00
Cincinnati       27	135	0.167	0.00
St. Louis        27	135	0.167	0.00
Milwaukee        26	136	0.160	1.00
Pittsburgh       25	137	0.154	2.00

Tie breakers
Chicago wins the series with Cincinnati 7 games to 6
Chicago wins the series with St. Louis 12 games to 1

To construct the scenario, we start with the current standings in the division:
Team             W	L	GL	PCT	GB
Chicago          0	0	162	0.000	0.0
Cincinnati       0	0	162	0.000	0.0
Milwaukee        0	0	162	0.000	0.0
Pittsburgh       0	0	162	0.000	0.0
St. Louis        0	0	162	0.000	0.0

Next, we show how the remaining series of games plays out in the scenario:

Chicago currently has 0 win(s) against Cincinnati and 0 loss(es).
Chicago wins 7 additional game(s) against Cincinnati and loses 6.
Chicago wins the series 7 games to 6.
Chicago wins 1 additional game(s) against teams outside the division and loses 109.

Chicago currently has 0 win(s) against Milwaukee and 0 loss(es).
Chicago wins 0 additional game(s) against Milwaukee and loses 13.
Chicago loses the series 0 games to 13.
Chicago wins 1 additional game(s) against teams outside the division and loses 109.

Chicago currently has 0 win(s) against Pittsburgh and 0 loss(es).
Chicago wins 7 additional game(s) against Pittsburgh and loses 6.
Chicago wins the series 7 games to 6.
Chicago wins 1 additional game(s) against teams outside the division and loses 109.

Chicago currently has 0 win(s) against St. Louis and 0 loss(es).
Chicago wins 12 additional game(s) against St. Louis and loses 1.
Chicago wins the series 12 games to 1.
Chicago wins 1 additional game(s) against teams outside the division and loses 109.

Cincinnati currently has 0 win(s) against Milwaukee and 0 loss(es).
Cincinnati wins 0 additional game(s) against Milwaukee and loses 13.
Cincinnati loses the series 0 games to 13.
Cincinnati wins 1 additional game(s) against teams outside the division and loses 109.

Cincinnati currently has 0 win(s) against Pittsburgh and 0 loss(es).
Cincinnati wins 7 additional game(s) against Pittsburgh and loses 6.
Cincinnati wins the series 7 games to 6.
Cincinnati wins 1 additional game(s) against teams outside the division and loses 109.

Cincinnati currently has 0 win(s) against St. Louis and 0 loss(es).
Cincinnati wins 13 additional game(s) against St. Louis and loses 0.
Cincinnati wins the series 13 games to 0.
Cincinnati wins 1 additional game(s) against teams outside the division and loses 109.

Milwaukee currently has 0 win(s) against Pittsburgh and 0 loss(es).
Milwaukee wins 0 additional game(s) against Pittsburgh and loses 13.
Milwaukee loses the series 0 games to 13.
Milwaukee wins 0 additional game(s) against teams outside the division and loses 110.

Milwaukee currently has 0 win(s) against St. Louis and 0 loss(es).
Milwaukee wins 0 additional game(s) against St. Louis and loses 13.
Milwaukee loses the series 0 games to 13.
Milwaukee wins 0 additional game(s) against teams outside the division and loses 110.

Pittsburgh currently has 0 win(s) against St. Louis and 0 loss(es).
Pittsburgh wins 0 additional game(s) against St. Louis and loses 13.
Pittsburgh loses the series 0 games to 13.
Pittsburgh wins 0 additional game(s) against teams outside the division and loses 110.

# Chicago Cubs' magic number
# Chicago's magic number
# Cubs' magic number
# MLB Playoff Race