Language and Time Barrier

So, today the teacher was telling us how to set up the exam room for a complete head to toe physical.  Tools blah blah, pap smear, ok,  etc.

She said "The doctor may, depending on the age of a male patient, decide to do a digital rectal exam."

A bunch of the younger students looked confused  "How?"

Teacher "The doctor inserts a finger into the rectum to feel the prostate"

Student "How is that digital?"  I could see the student thought like a digital clock kind of thing

The teacher holds up her hand "These are called DIGITS"