What tool do you use to measure in inches?
Rulers, yardsticks, and tape measures that are not metric calibrated do a fine job.
Assuming that the hallway is 30 m long. 30mx100= 3000 cm . Then divide 3000 cm by 2,54= result: 1181,1023622047244094488188976378 in = (Firstly you have to use any measuring tool to find the length of the hallway in meters, or you may get the final reading in inches if the measuring tape tool has divisions in centimeters and inches. Usually they have divisions on foot and cm)