The problem of calculating stoichiometric coefficients in a chemical equation can be solved by standard methods and the method of multidimensional vector space, but good knowledge of vector algebra is required. In this paper, the authors proposed a matrix method and other treatment of the problem was given as the authors' own interpretation. A matrix was formed in the form of base using all the elements which take place in a chemical reaction, after which the matrixes of all the chemical compounds were determined based on numerical indexes and element symbols. This approach enables the setting of a principal matrix equation based on a mathematical approach. The solutions of this matrix equation are the desired stoichiometric coefficients that form a balanced equation. A new approach to tabular solving is presented. This method, compared to existing standard methods, is faster, simpler, and more effective, especially for complex chemical equations. The method was tasted on examples from inorganic chemistry and metallurgy.

UNLABELLED Antrochoanal polyp (ACP) is a benign lesion which arises from the mucosa of maxillary sinus, fills it and expands through natural ostium towards choana protruding in the epipharynx. OBJECTIVE to present our experience in endoscopic surgery of ACP. MATERIAL AND METHODS prospective study included 24 patients operated at the Institute of Otorinolaryngology and Maxillofacial surgery, Clinical Center of Serbia, Belgrade, in the period 2002-2004. Subjective symptoms, endoscopic and CT findings were evaluated postoperatively, following up the patients in the period 12-20 months. Subjective difficulties of patients were tested by 100mm-analogue scale, while endoscopic and CT findings were demonstrated by three-stage scale from 0 to 2. Applying the technique of ACP extraction in Trendelenburg's position and approaching the part which protrudes in the epipharynx, we successfully removed the endonasal part by means of curved forceps for epipharyngeal biopsy. By endoscopic middle meatotomy, the natural ostium of maxillary sinus was expanded and pathological process from the very sinus was successfully removed. RESULTS only one female patient had the majority of symptoms after the operation, while all others had no complaints. Endoscopic and CT findings were normal in all patients at the latest control, without any signs of ACP recurrence. There were no intraoperative or postoperative complications. CONCLUSION minimal damage to sinus mucosa due to forceps is lesser problem than complications developed upon creating even the miniature opening in the canine fossa. Using this technique, a dexterous surgeon may successfully extract patho-logical process with minimal incidence of recurrence, and, more important, with no complications and maximally fast recovery of patients.