How long was I in the garden?

[Grandma Ruth]

This sounds like a made-up riddle, but it actually happened to me today. I took off my analogue watch before going to do the garden. When I came back and put it on, for a moment I thought it had stopped - but no, it was telling the right time. How long did I spend in the garden?

[RulerofRails]

12 hours?

[Grandma Ruth]

12 hours?

Moi? In the garden for 12 hours?!!! I just realised this could have happened with a few different times. I emailed my family about it at 13.10, so they had an extra clue, as they know I can't remember anything for more than a few minutes.

[Gumboots]

Ok, if your memory is that bad, and it wasn't 12 hours, my guess is less than a minute.

[RulerofRails]

Can I guess again? 1 hour and 5 minutes.

[Grandma Ruth]

That's it, RoR! More or less, I can't do the maths really, but it was five past eleven and then it was five to one!!! No prize, unfortunately, but you're the only person of my acquaintance who got it. That includes my grandson who just graduated today - in Maths! - from St Andrew's University!

[RulerofRails]

Ah. 11:05 till 12:55 is 1 hour and 50 minutes. So you mistook one watch hand for the other. Not that hard to do.

But you shouldn't give me credit. I had supposed that you saw the time at 5 past one and then next time it was 10 past two.

[Gumboots]

There were so many options that I just went with the obvious joke answer.