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 Brain Teaser Square Extensions  In the university hall, Professor Tupolev meets Professor Grigolev, a long-time friend who has recently joined the faculty. Professor Tupolev : Glad to see you, Grigor. I'm in a hurry now, I'll call you later. What is your extension ? Professor Grigolev : 2025, Professor.... Professor Tupolev : Goodness ! A strange number. Sum up its first two digits with the second two you obtain 45, which is the square root of the number itself ! Professor Grigolev : Really fascinating, Maybe we could discuss it later ... By the way, Tupolev, what is your telephone number here ? Professor Tupolev : Very simple, my dear Grigor. It is the next four-digit number after 2025 which has the same wonderful properties. Wath is Professor Tupolev's extension number? By courtesy of PFI Matteo Rosa The answer to the last Challenge Brain Teaser: Reaching Home. The distance between Tupolev's and Igor's birthplaces cannot be more than 10.000 kilometers (the Earth being a round globe with a circumference of 40.000 kilometers).  |
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