Recently I did a measurement experiment where I measured the diameter of a piece of wire using a micrometer. I tested it 4 times. I got 0.87, 0.89, 0.90,0.90 respectively. The units being millimeter. My micrometer has a least count of 0.05mm. The uncertainty of a single measurement would then be plus or minus 0.05mm. However how would I express the uncertainty after taking the average of the 4 values I stated above. Would it still be plus or minus 0.05mm? Or what could it be? I'm slightly confused.