Well Bob, if math is black magic and voodoo to you, I hope you don't have a job where peoples' lives depend on precise measurements.

And I gues you can set your clock to any arbitrary time you choose, if you don't have any where to be or anything to do.

When you show up at your 4PM doctor's appointment at 6:30PM, you can just show him your clock says 3:55. I'm sure he'll see you anyhow.