I had (still have) a circular slide rule that gave me 5-6 digit accuracy. But for most engineering work 3-digit accuracy may be enough. (Do you really want to trust your life to something that doesn't have more than 1% design margin?)
You've got to love the innumeracy of the reporter on this article:
by Wednesday, the contamination had jumped to 17,000 parts per liter.
Ah yes, parts per liter. One of those quaint old-fashioned units of concentration, I guess, like horsepower per cubit. I wish someone could remind me how we convert to a more familiar unit like grams per liter, moles per liter, parts per million.
I suspect they mean 17,000 atoms per liter. Since a liter of water has about 3.33*10^23 molecules or 6.66*10^23 hydrogen atoms, That would make the tritium concentration 1 per 3.91*10^19 hydrogen atoms. I wouldn't count on getting rich by collecting the tritium.
"'Tis true, 'tis pity, and pity 'tis 'tis true." -- Poloniouius, in Willie the Shake's _Hamlet, Prince of Darkness_