Seattle Mariners First-Place Elimination Scenario
Seattle must win 10 more games (56 total) to avoid elimination from first place.
Here are the final standings in a scenario in which Seattle finishes in first place with 56 wins:

Team             W	L	PCT	GB
Seattle          56	106	0.346	0.00
Houston          56	106	0.346	0.00
LAAngels         55	107	0.340	1.00
Oakland          55	107	0.340	1.00
Texas            55	107	0.340	1.00

Tie breakers
Seattle wins the series with Houston 10 games to 3

To construct the scenario, we start with the current standings in the division:
Team             W	L	GL	PCT	GB
Seattle          46	44	72	0.511	0.0
Texas            45	44	73	0.506	0.5
Houston          44	47	71	0.484	2.5
Oakland          41	48	73	0.461	4.5
LAAngels         36	54	72	0.400	10.0

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

Houston currently has 3 win(s) against LAAngels and 4 loss(es).
Houston wins 0 additional game(s) against LAAngels and loses 6.
Houston loses the series 3 games to 10.
Houston wins 1 additional game(s) against teams outside the division and loses 46.

Houston currently has 3 win(s) against Oakland and 3 loss(es).
Houston wins 4 additional game(s) against Oakland and loses 3.
Houston wins the series 7 games to 6.
Houston wins 1 additional game(s) against teams outside the division and loses 46.

Houston currently has 1 win(s) against Seattle and 7 loss(es).
Houston wins 2 additional game(s) against Seattle and loses 3.
Houston loses the series 3 games to 10.
Houston wins 1 additional game(s) against teams outside the division and loses 46.

Houston currently has 5 win(s) against Texas and 2 loss(es).
Houston wins 5 additional game(s) against Texas and loses 1.
Houston wins the series 10 games to 3.
Houston wins 1 additional game(s) against teams outside the division and loses 46.

LAAngels currently has 5 win(s) against Oakland and 6 loss(es).
LAAngels wins 0 additional game(s) against Oakland and loses 2.
LAAngels loses the series 5 games to 8.
LAAngels wins 0 additional game(s) against teams outside the division and loses 47.

LAAngels currently has 2 win(s) against Seattle and 4 loss(es).
LAAngels wins 7 additional game(s) against Seattle and loses 0.
LAAngels wins the series 9 games to 4.
LAAngels wins 0 additional game(s) against teams outside the division and loses 47.

LAAngels currently has 3 win(s) against Texas and 0 loss(es).
LAAngels wins 6 additional game(s) against Texas and loses 4.
LAAngels wins the series 9 games to 4.
LAAngels wins 0 additional game(s) against teams outside the division and loses 47.

Oakland currently has 2 win(s) against Seattle and 4 loss(es).
Oakland wins 7 additional game(s) against Seattle and loses 0.
Oakland wins the series 9 games to 4.
Oakland wins 0 additional game(s) against teams outside the division and loses 51.

Oakland currently has 4 win(s) against Texas and 3 loss(es).
Oakland wins 2 additional game(s) against Texas and loses 4.
Oakland loses the series 6 games to 7.
Oakland wins 0 additional game(s) against teams outside the division and loses 51.

Seattle currently has 2 win(s) against Texas and 4 loss(es).
Seattle wins 7 additional game(s) against Texas and loses 0.
Seattle wins the series 9 games to 4.
Seattle wins 0 additional game(s) against teams outside the division and loses 46.

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