Getting familiar with the new scanner on iOS11 on my iPhone
Older Baby-Boomers: When was the last time you had a portrait taken with your spouse?

How accurate are blood pressure readings taken at Sam's Club or a drug store?

My blood pressure reading.
This is my blood pressure reading taken at a neighborhood RiteAid from a few days ago.

I did a quick stop at the neighborhood Rite Aid a few days ago and spotted a machine where I could take my blood pressure.  Ordinarily, I would not take the time, but I couldn't resist.  This was my reading.  It seems to be pretty decent.

How accurate are these machines?  Is it like the difference between stepping on the scale at home and the one at the doctor's office where the numbers seem to be inflated?  Just curious.