**About mathematical zanzibar in the regions of Ukr**aine

As you know, September 16 in Kiev will be a traditional mathematical zanzibar, as the first event of the XV Kiev tournament of mathematical battles named after Lesya Rubleva. We propose to hold this event also in all regions who are not indifferent to mathematical competitions. We will gladly share the task, or you can develop your own tasks. If this happens in several regions, maybe next year we will try to somehow connect all the cities that will hold it in a single table, and thus we can get an All-Ukrainian event, where the result of the team in Chernivtsi will also affect the team's result in Kyiv and vice versa. But it can turn out with mutual consent for such. Perhaps in Poltava it is much more interesting to compete with each other, without involving teams from other cities. But it is not important, the most important thing is that as many cities of teams, participants, etc. take part in it. The fact is that the mathematical zanzibar is not a serious mathematical competition, but it is interesting both in tasks, by the method of conducting, and by counting points, etc. Therefore, after such a start, children may want to continue to participate in various mathematical and not only competitions throughout the year.

__Rules of mathematical zanzibar __

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**is a team competition. Each team consists of 6 or fewer players (in case of exclusion, with the permission of the organizing committee, the team may consist of more participants). Before starting zanzibar, teams are given all the tasks (from 10 to 20) at once, which they solve within 2 hours (or a shorter period of time, if they are junior students). The jury only checks the answer. If it is true, it is considered that the command solved this problem correctly, if the answer is not correct or complete, then the task is counted as unsealed.**

*athematical Zanzibar*At the beginning of Zanzibar, each task is estimated at 10+N points, where N is the number of teams participating in the competition. Further accrual of points for tasks and the cost of the task are assessed as follows. If the team is the first to solve, for example, task No. 5, then it receives 10+N points for it and the cost of the problem becomes 9+N. If another team solved it correctly, then for it 9+N points is received not only by her, but also instead of 10+N, 9+N points are set to the team that unleashed it earlier. If another team solved it correctly, then all three teams will receive a task of 8+N points. If some team incorrectly solved this problem, then it gets 0 points for it, and all the teams that solved it by 1 point more. Thus, in the process of zanzibar, the next team that solved a certain problem correctly reduces by 1 point the result on this task of each other team and this team receives the same score for this task as all other teams. If the next team solved the problem incorrectly, then all teams that have already solved this problem correctly receive 1 point more than this task. Therefore, at the end of the zanzibar, the price of each problem is calculated by the formula: 11+N–C+L, where C is the number of commands that solved the problem correctly, and L is the number of commands that solved the problem incorrectly.

The final result of the team consists of the sum of points scored for each task – a positive number for a correctly solved task, and 0 for an incorrectly solved task, or for a task to which this team did not provide an answer to the jury.

If only 1 command correctly solved a problem, then the cost of this task at the end of the zanzibar is doubled for it. This should encourage teams to try to solve the most difficult tasks correctly.

The course of the game will look more interesting if all teams play in the same large audience, and the current result is highlighted through a projector on the screen.

**Information for** the jury

I remind potential jury members who wish to assist in the ongoing jury registration. Already on September 30, during the oral mathematical olympiad within the XV Kyiv Tournament of Mathematical Battles named after Lesya Rubleva, we need a qualified professional jury in sufficient quantities.

Registration of jury members for 2018-19 Olympiad years

Mathemati__cal Zanzibar in Kiev__

**For Kyiv reside**nts, let me remind you that the registration of participating teams is underway, which will last until 14:00 on Wednesday, September 12, 2018.

Registration for mathematical zanzibar

Glory to Ukraine!

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