Surely everyone knows that the result of multiplying two negative numbers is positive. The formula “minus times a minus is a plus” or **“negative times a negative is a positive”** was put into our heads during the early school years. However, the teachers have forgotten to explain why this is the case, and to pass the motivation of mathematicians who defined the arithmetic of negative numbers.

#### ⭐️ Multiplication as a short notation of repeated addition

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