1.8

I had just finished putting away my wallet and was walking out of the manicurist's when the receptionist came chasing after me. She grabbed my arm, reached up over her head with a gesture to indicate "tall," then ran into the shop, procured a pen and notepad, ran back out, and held out to me a slip reading "1.8?"

I laughed and wrote back "1.75" with a little drawing of a high-heeled shoe. She smiled, nodded vigorously, and ran back inside to confirm her guess with the other receptionist.