Blimey........
Well, here's a trick. Take time, and turn it into a decimal. 1hr = 1.0, 6 minutes = 0.1 etc (you get my drift). Do the maths, then if you feel the urge, convert it back to "normal" time. I just log it as decimal time, as I like an easy life, and the CAA / FAA don't have a problem with me doing it.....
