How Mandarin numbers work: nought to ninety-nine

To 99, Mandarin numbers spell themselves: no teens to memorise, no special words for the tens. Eleven syllables and one rule cover prices, ages and times. After that come four traps: a zero you have to say, a second word for two, a 一 (yī) that changes tone, and big numbers counted in ten-thousands.

Nought to ten

• 一yīone
• 二èrtwo
• 三sānthree
• 四sìfour
• 五wǔfive

Each is one syllable with one tone, and a wrong tone is a wrong price. The pair that trips everyone is 四 (sì, four) and 十 (shí, ten). Chinese children drill it with a tongue-twister:

• 四sì是shì四sì，十shí是shì十shí。 (Sì shì sì, shí shì shí.) - Four is four, ten is ten.

Say sì short and falling, shí rising with the tongue curled back.

Eleven to ninety-nine: the number spells itself

A digit after 十 (shí) adds; a digit before it multiplies.

There is no catch in the teens. They even have a name built from the rule, 十几 (shíjǐ), ten-and-a-few:

• 他tā十shí几jǐ岁suì。 (Tā shíjǐ suì.) - He's in his teens.

Why 一 (yī) changes tone

一 (yī) is first tone on paper and has three pronunciations in speech. The character never shows it.

Dictionaries write the base tone yī; learner materials, this page included, write the tone you say. 不 (bù) does the same before a fourth tone, as the negation page shows.