let me see(also let's see) used when you are trying to remember something
[TahlilGaran] Dictionary of Contemporary English ▲
let me see informal 1. Let us find out by trying or performing an action.
Let me see if you can jump over the fence. 2. Give me time to think or remember.
I can't come today. Let me see. How about Friday? Let's see. Where did I put the key? [TahlilGaran] English Idioms Dictionary ▲