OAKLAND, Calif. — With a postseason berth in their sights, the Athletics are leaving nothing to chance.

Marcus Semien had three hits and a career-high five RBIs, Stephen Piscotty homered and drove in four runs and the A’s hammered the Angels 21-3 on Thursday.

The A’s reduced their magic number for clinching a playoff berth to five. Since June 15, they are a major-league-best 58-25.

Going into Thursday, the A’s trailed the Astros by four games in the AL West, led the Rays by 51/2 games for the second wild-card spot, and were 21/2 games behind the Yankees for the first wild card.

The Angels were outscored 31-2 in the last two games of the series.

“Honestly, when I saw the score up there on the board, it looked like a football score,” Piscotty said. “It doesn’t happen all that often, but it’s a crazy game.”

The A’s tied a team record for runs first set on June 18, 2000, against the Royals.

Piscotty was 2-for-3 with a three-run homer. He’s 4-for-6 with two home runs and nine RBIs in his last two games and has seven home runs and 22 RBI this month. Matt Chapman was 2-for-4 with a double and two RBIs.

Edwin Jackson (6-3) struck out seven, walked three and gave up two runs in 51/3 innings of three-hit ball.

“When you’re getting runs like that, it’s always fun,” Jackson said. “The main thing you want to do is continue to pitch and see how many shutout innings you can have to get them back in the dugout to continue to hit.”

Mike Trout hit his 36th home run for the Angels. They have lost five of their last seven.