yāo
1 in numbers
Phone, room and flight numbers are read one digit at a time. The digit 1 becomes 幺 (yāo), because 一 (yī) is easy to mishear as 七 (qī).
yāo
1 in numbers
yāo sān bā
138 — the start of a number
diànhuà hàomǎ
Phone number
nǐ de diànhuà hàomǎ shì duōshao?
What is your phone number?
一 (yī) and 七 (qī) are easy to confuse by ear, especially over the phone, so 1 is said as 幺 (yāo) in numbers.
你的电话号码是多少? (nǐ de diànhuà hàomǎ shì duōshao?) — "what is your phone number?".
110, read 幺幺零 (yāo yāo líng). Fire is 119 and an ambulance is 120.
Tomyo
Numbers stick when you use them. Tomyo reviews your words on a schedule so what you learn is still there a month later.