Several tens/hundreds/thousands (数十/数百…)

Structure 数 + power of ten (十/百/千/万) + measure + noun

数 (shù) before a power of ten expresses a high but unspecified quantity: 数十 = "several tens", 数百 = "hundreds", 数千 = "thousands", 数万 = "tens of thousands". 数百名志愿者 = "hundreds of volunteers". It's a productive, very journalistic frame: it pairs with any power of ten plus its measure word. Don't confuse it with 无数 (wúshù, "countless"), a fixed item meaning an uncountable amount, not "a few hundred".

Examples

数shù百bǎi名míng志zhì愿yuàn者zhě参cān与yù了le救jiù援yuán。
Hundreds of volunteers took part in the rescue.
这zhè项xiàng技jì术shù已yǐ申shēn请qǐng数shù十shí项xiàng专zhuān利lì。
This technology has already filed several dozen patents.
展zhǎn览lǎn吸xī引yǐn了le数shù千qiān名míng游yóu客kè前qián来lái。
The exhibition drew thousands of visitors.
洪hóng水shuǐ使shǐ数shù万wàn居jū民mín被bèi迫pò撤chè离lí。
The flood forced tens of thousands of residents to evacuate.

Levels are indicative: they follow the standard Chinese Grammar Wiki (AllSet Learning) progression, not an official HSK 3.0 mapping. We never assign levels by eye.

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