The 16th-placed Baggies currently sit just above Crystal Palace on goal difference, with both teams on 28 points.
Foster told the WBA website: "I think maybe 36 or 37 points will probably do it this season, it's really tight down there, so first things first we need to get three points from the Cardiff game.
"Then our run-in isn't as bad as some other teams - we've got Arsenal away, Tottenham at home and Man City away but the rest are all teams around us so we need to remain positive.
"Yeah, they're massive. Each game is a monster game in all honesty.
"We've got to put Hull behind us now, Cardiff is another six-pointer.
"If you look at the Swansea game we did so well there, we just need to take a bit of confidence from that really.
"I thought we did well up until the penalty on Saturday, the penalty was a game changer. So there are some positives to take."
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