Replace the question mark with a numberMATH PUZZLE: Can you replace the question mark with a number?
Correct answers: 66
The first user who solved this task is Manguexa Wagle.
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Camera rocket apparatusIn 1904, a rocket apparatus for taking photographs was patented in the U.S. by Alfred Maul of Dresden, Germany (No. 757,825). He described how, with its timing device, it would automatically take photographs giving bird's-eye views of the ground, with the camera mounted obliquely to the ground during the nearly-vertical upward flight. Maul acknowledged a prior patent for a camera rocket (German No. 64,209 to Ludwig Rohrmann granted 14 Jul 1891) and there were others. However, beginning his practical work in 1901, Maul is known to have actually constructed workable camera rockets, and achieved world-wide fame. He improved his design in U.S. patent 847,198 on 12 Mar 1907. His purpose was observational use in military applications, but was obsoleted by aircraft used in WW I.«