First of all, the ball contacted by the tenderer is determined in advance, such as the No.6 ball. There are two ways to touch the ball. The first one hides a No.6 ball directly in your hand and pretends to take it out of the box. Cracking method: When the tenderer finishes drawing and asks to check the number of balls in the box, if there is still a No.6 ball in the box, it means that something is fishy. Secondly, if there is something wrong with the box, the staff will hide the No.6 ball prepared in advance in a special position in the box, so that they can get the No.6 ball directly. Cracking method: the representative selected by the bidder shall check whether there is a black box before the tenderer draws it.
Secondly, the agency company extraction is nothing more than the above two modes of operation.
Summary: As long as we check whether the initial number of balls is consistent with the number after extraction, and check whether there is a problem with the extracted props, we should be able to find out the problem.