Seattle Mariners First-Place Eliminiation Scenario
Seattle must win 21 more games (38 total) to avoid elimination from first place.
Here are the final standings in a scenario in which Seattle finishes in first place with 38 wins:

Team             W	L	PCT	GB
Seattle          38	124	0.235	0.00
Texas            38	124	0.235	0.00
Houston          37	125	0.228	1.00
Los Angeles      37	125	0.228	1.00
Oakland          37	125	0.228	1.00

Tie breakers
Seattle wins the series with Texas 9 games to 4

To construct the scenario, we start with the current standings in the division:
Team             W	L	GL	PCT	GB
Seattle          17	14	131	0.548	0.0
Texas            16	15	131	0.516	1.0
Oakland          15	17	130	0.469	2.5
Los Angeles      11	20	131	0.355	6.0
Houston          10	20	132	0.333	6.5

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

Houston currently has 0 win(s) against Los Angeles and 0 loss(es).
Houston wins 6 additional game(s) against Los Angeles and loses 7.
Houston loses the series 6 games to 7.
Houston wins 0 additional game(s) against teams outside the division and loses 87.

Houston currently has 0 win(s) against Oakland and 0 loss(es).
Houston wins 13 additional game(s) against Oakland and loses 0.
Houston wins the series 13 games to 0.
Houston wins 0 additional game(s) against teams outside the division and loses 87.

Houston currently has 0 win(s) against Seattle and 0 loss(es).
Houston wins 5 additional game(s) against Seattle and loses 8.
Houston loses the series 5 games to 8.
Houston wins 0 additional game(s) against teams outside the division and loses 87.

Houston currently has 4 win(s) against Texas and 3 loss(es).
Houston wins 3 additional game(s) against Texas and loses 3.
Houston wins the series 7 games to 6.
Houston wins 0 additional game(s) against teams outside the division and loses 87.

Los Angeles currently has 0 win(s) against Oakland and 0 loss(es).
Los Angeles wins 6 additional game(s) against Oakland and loses 7.
Los Angeles loses the series 6 games to 7.
Los Angeles wins 0 additional game(s) against teams outside the division and loses 79.

Los Angeles currently has 0 win(s) against Seattle and 0 loss(es).
Los Angeles wins 11 additional game(s) against Seattle and loses 2.
Los Angeles wins the series 11 games to 2.
Los Angeles wins 0 additional game(s) against teams outside the division and loses 79.

Los Angeles currently has 0 win(s) against Texas and 0 loss(es).
Los Angeles wins 2 additional game(s) against Texas and loses 11.
Los Angeles loses the series 2 games to 11.
Los Angeles wins 0 additional game(s) against teams outside the division and loses 79.

Oakland currently has 0 win(s) against Seattle and 0 loss(es).
Oakland wins 10 additional game(s) against Seattle and loses 3.
Oakland wins the series 10 games to 3.
Oakland wins 0 additional game(s) against teams outside the division and loses 81.

Oakland currently has 2 win(s) against Texas and 1 loss(es).
Oakland wins 5 additional game(s) against Texas and loses 5.
Oakland wins the series 7 games to 6.
Oakland wins 0 additional game(s) against teams outside the division and loses 81.

Seattle currently has 2 win(s) against Texas and 1 loss(es).
Seattle wins 7 additional game(s) against Texas and loses 3.
Seattle wins the series 9 games to 4.
Seattle wins 1 additional game(s) against teams outside the division and loses 81.

# Seattle Mariners' magic number
# Seattle's magic number
# Mariners' magic number
# MLB Playoff Race