左右 / 上下 / 来: about, around
数量表达 / numbers & quantities
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
Number + (M) + 左右/上下 | 十/百 + 来 + M + N
To give an approximation:
• 左右 ("left-right"): after number + measure/unit: 三十岁左右、八点左右. The most common.
• 上下 ("up-down"): mostly for age, weight, height: 五十岁上下.
• 来: after a round number (十、二十、一百…) and before the measure word: 二十来个人 (twenty-odd people).
大概 + 左右 together (大概三十个左右) is common in speech but redundant in careful writing.
Examples
中国六十岁以上的老人有两亿多，占总人口的百分之二十左右。
Zhōngguó liùshí suì yǐshàng de lǎorén yǒu liǎng yì duō, zhàn zǒng rénkǒu de bǎi fēn zhī èrshí zuǒyòu.China has over 200 million people aged 60+, around 20% of the population.
他看起来四十岁上下。
Tā kàn qǐlái sìshí suì shàngxià.He looks about forty.
会议来了二十来个人。
Huìyì lái le èrshí lái ge rén.Twenty-odd people came to the meeting.
Common mistakes
✗ 左右三十岁 → ✓ 三十岁左右 (左右 goes after).
✗ 二十个来人 → ✓ 二十来个人 (来 before the measure word).
✗ 八点上下 for clock time → ✓ 八点左右。