Why my unit is automatically converting to something else?

I want to assign my a unit for my homework, but this stupid system always automatically adding up something. 

for example, when I type 1 in, it gives me 12 1/ft in. If it's in SI unit, it will give me  39.97  1/m in. 

why is this software add up something redundant? i just want to type whatever the unit i want. what's wrong with this software?