In general, it's pretty easy to get the 8x or 19x correctly — these are the large dimensions. So really, you are only looking at being wrong on the 102, and off

In general, it's pretty easy to get the 8x or 19x correctly — these are the large dimensions. So really, you are only looking at being wrong on the 102, and off by two (100-104) is not such a big difference (1.52M-1.58M). Once you realise that the error bars are small (and it was mostly intuitive for me, probably looking at counting up to a hundred, so a few percent off is not a big deal), you stop worrying about the uncertainty as much ;-)