He made a mental note of his answer, and went in again.

She made a mental note to find out the current rate.

I made a mental note to keep my eye on him.

So after taking a few mental notes on the man, she went back to work.

She could almost see him making mental notes for changes.

Then I looked at my watch and made a mental note of the time.

I made a mental note to be on the watch for such.

He went right on talking while I took mental notes.

He didn't need to make a mental note to look into the idea later.

He made a mental note to keep his eyes on her just in case.