The description says you should "round down to the nearest second" so may be the rounding strategy is the case?

Or girls :)
But my first question was meant as kind of an intro for the actual question, but maybe that wasn't clear. My apologies!
I was just wondering if one of those 756 Ruby-programmers had the same struggle and if they could give me a hint on how to solve it because (normally) the math should add up and it is frustrating I'm only off by 1sec.

Look at the top of the page and you will see that 756 guyss solved the Ruby kata.