Confuse!!!!! Changing half percent into fractions..?

I was doing a math problem and it said write each percent as a fraction in its lowest term.. One problem said do 12(1/2)% or 12 and a half percent.. I thought the answer would be 25/2 cuz of just turning it into a improper fraction.. But they have 1/8.. Do anyone know how to explain how it's 1/8?