Question 1
Three students of class X, Dần, Mão and Thìn, while out walking see a driver violate traffic regulations. None remembers the entire registration number, but each remembers one feature. Dần remembers that its first two digits are equal. Mão remembers that its last two digits are equal. Thìn asserts that the four-digit number is a perfect square. Let us try to find that number.