Breakdown of Его пунктуальность удивляет: он пришёл в десять минут первого.
он
he / it (for a masculine noun) / it (for a neuter noun)
десять
ten
минута
minute
в
on / during (a time period)
Questions & Answers about Его пунктуальность удивляет: он пришёл в десять минут первого.
Why does the phrase for "past twelve" use the word первого (first)?
In traditional Russian time-telling, for the first half of the hour, you state how many minutes of the upcoming hour have passed. The hour right after 12:00 is considered the "first hour" of the new cycle. So, десять минут первого literally means "ten minutes of the first (hour)."
Why is первого in the genitive case?
It literally translates to "of the first [hour]." The word час (hour) is implied but almost always left out. To say "of the first," we put the ordinal number первый into the genitive case, which becomes первого.
Why do we need the preposition в before the time here?
To say that an event happens at a certain time, you use в + Accusative case. If you just said десять минут первого, it would mean "It is ten past twelve." Adding в tells us he arrived at that time. (Note that the accusative form of десять is identical to its nominative form).
Why does the sentence use the active verb удивляет (surprises) to mean "is surprising"?
In Russian, it is very common to use an active verb without a direct object to express a general characteristic or fact. Его пунктуальность удивляет literally means "His punctuality surprises [people in general]," which translates perfectly to "His punctuality is surprising."