Do you understand that "x unit1/unit2"meansthat a length of 1 "unit 2" is the same as x "unit1"s? "12.56 km/1ft" is wrong- 12.56 kilometers is the total distance, not the number of kilometers in a foot. "104.6 ft/1 in" is incorrect (where did you get 104.6?), there are 12 in in a foot so it would be 1 ft/12 in= 1/12 ft/in= 0.0833 ft/in . "87.22 in/1 cm" is wrong. There are (approximately) 2.5 cm in an inch so 1/2.5 inches per cm or 0.4 in/cm. "34.34 cm/1 km" is wrong. There are 100 cm in a meter and 1000 m in a km so there are 100000 cm in a km so 100000 cm/km.

You should have (12.56 km)(100000 cm/km)(0.4 in/cm)(0.0833 ft/in)

(That doesn't give exactly 41287.35 because there are serious roundoff errors in a calculation like that.)

I really wonder where in the world you got those numbers!