Pattern:
数 ('several') + numeric unit. Build out the whole family:
数十 (several dozen / tens),
数百 (several hundred),
数千 (several thousand),
数万 (tens of thousands),
数十万 (hundreds of thousands),
数百万 (millions). Note that Chinese counts in
万 (10,000) — so 'a million' is
一百万 and 'hundreds of thousands' literally reads 'several ten-ten-thousands.'
