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Professor O.'s space flight

Professor O. goes on a space flight. He lands on a distant planet and gets a friendly welcome from the inhabitants. Soon they and their visitor manage to start a communication, and O. attends a mathematics lesson in a school. The teacher has written a calculation on the blackboard:



O. asks the teacher to explain the symbols in the calculation. Counting bars turns out to be the best intergalactic communication method. On the next blackboard you can see a few examples:



As soon as O. has understood all symbols in the calculation he writes down the calculation substituting the symbols by the familiar arabic numerals:



But the resulting equation seems strange to O. He sends a message to his colleague and number theory specialist Professor S. and asks him for his opinion. S. is a little bit mean and hides the solution behind the cryptic advice: "Count the fingers of your hosts." O. follows this advice. What will he discover?

Solution