Sorry to butt in, but I only caught up to this game now.
852 = ((5 * 10 - 10) * 7 + 4) * 3
Given a specific target number, there is always a two in three chance or higher (generally significantly higher) that the six numbers you get can hit that number precisely. Getting within 10 of the target is virtually guaranteed, unless you hit a terrible set, like {1, 1, 2, 2, 3, 3}.