How does the corona virus multiply so quickly? It is estimated that each person is infected on average Infects three other people. Let's see how the number of new cases increases over time. Imagine a large chessboard and put the first infected person in the first house. It affects three other people (in the case of Corona, the current approximation is 3 people). These three people together infect 9 other people. These nine people together will infect 27 people. What is this Meaning? The increase in cases becomes faster over time! This growth in numbers is called exponential growth. For example, in New York City during March–May 2020, approximately 203,000 laboratory-confirmed COVID-19 cases were reported to the NYC Department of Health and Mental Hygiene (DOHMH). We can write a very simple formula of the whole population according to the condition of the disease as follows: If (N) is the total population; (S) populations that can catch the disease; (I) the patient population; Name (R) an improved or dead population, then we come to the following simple relation: N=S+I+R

Therefore, to calculate the exponential growth accurately, the following formula must be used.

ds.dt = -SNI

Bärwolff, Günter. “Mathematical Modeling and Simulation of the COVID-19 Pandemic.” *MDPI*, Multidisciplinary Digital Publishing Institute, 13 July 2020, www.mdpi.com/2079-8954/8/3/24/htm.

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