SESTERCES

We saw two mentions of sesterces in this section.

sestertius, -i [<*semis-tertius] as a noun [OLD 2]:
A coin or unit of money, equivalent to 2 ½ asses or a quarter of a denarius (4 asses after 217 BCE when a denarius was divided into 16 asses); sestertius nummus, a sesterce piece.

quadringenis nummis: masc. abl. plur. of the adjective quadringeni, -ae, a, four hundred (400).  and the noun nummus, -i. Suetonius is thus referring to 400 sesterce pieces.

This gift to the public, congiarium, was originally a distribution of wine or oil made to the people by magistrates. Julius Caesar was the first to convert it into one of cash. What started out as an act of munificence became an obligation for the emperors if they wanted to maintain popular support (see K. R. Bradley’s historical commentary on Suetonius’ Life of Nero, p. 75).

sestertius, -a, -um as an adjective [OLD3]:
The adjective is used with multiples of thousands, milium–milia. The milia often undergo an ellipsis.

quingena: neutr. acc. plur. of the adjective quingeni, -ae, a, five hundred (500). “et quibusdam quingena… constituit” thus refers to 500’000 sesterces where the thousands are ellipted.