How many hours was the flight?

The closest I came to an engine out was a fuel starvation situation
when I was a student pilot many moons ago. For my long solo X-country,
I planned the flight carefully so that I would have more than 60
minutes of fuel upon returning. However, after the plane was refueled
upon my final landing at my starting point, the owner of the plane (who
also ran the flight school) informed me that I was close to zero fuel.
He knew because he refueled the plane to near full capacity!

We determined that this happened because I had not leaned the engine,
but used performance figures from the POH that required proper leaning!
My instructor (I was his first student after he received his CFI
ticket) had not yet trained me on leaning procedures...