To indicate an approximate number, the NUM position can be filled with a cardinal number and a hedge word, as exemplified below,
那二十多杯茶
na4 er4shi2 duo1 bei1 cha 2
that twenty more CL tea
‘those over twenty (between 21 and 29) cups of tea’
约三百五十名士兵
yue1 san1bai3 wu3shi2 ming2 shi4bing1
about three_hundred fifty CL soldier
‘about three hundred and fifty soldiers’
Another way is to fill with two consecutive basic digits, for instance,
七八张桌子
qi1ba1 zhang1 zhuo1zi0
seven_or_eight CL desk
‘a few (roughly seven or eight) tables’
A third way is to use the quantifier 数 shu4 ‘several’ or 几 ji3 ‘several’, as shown below,
有数十名矿工正在井下作业。
you3 shu4shi2 ming2 kuang4gong1 zheng4zai4 jing3 xia4 zuo4ye4
YOU several_ten CL miner ZAI well under work
‘Several dozen miners were working in the tunnels.’
广场上聚集了几百只鸽子。
guang3chang3 shang4 ju4ji2 le0 ji3bai3 zhi1 ge1zi0
square on gather LE several_hundred CL pigeon
‘Several hundred pigeons gathered at the square.’
Reference:
Shi, Dingxu. 2016. Nouns and nominal phrases. In A Reference Grammar of Chinese, eds. by Chu-Ren Huang and Dingxu Shi. Cambridge University Press.