Riddle: A long hallway has 43 light bulbs on the ceiling. Each light bulb has a pull cord that turns it on and off. All the lightbulbs start turned off. 43 people go down this hallway. The first person pulls every cord: 1,2,3,4... (now all bulbs are on) The second person pulls every other cord: 2,4,6,8... The third person pulls every third cord: 3,6,9,12... And so on with the rest. Finally the 43rd person pulls cord 43. Which bulbs are on after all the people have passed through? Feel free to use the Sudoku Grid to work out the answer. Sudoku: Mark the final lit up bulbs in the Sudoku grid. (The hallway starts with Bulb 1 in R1C3) Lit hallway cells are brighter (higher) than their hallway neighbors. Hallway cells get darker (lower) as you get further away from a lit cell. Between every two lit cells in the hallway there will be a darkest (lowest) cell. It can be anywhere between the two lit cells. Arrows show the way through the hall. Digits along an arrow sum to the circled digit.