你电话号码是多少？

What's your phone number?

What is your phone number?

What's your telephone number?

Source: Tatoeba

Sentence Composition

=1 你 nǐ you (informal, as opposed to courteous 您 nín)
=1 你 nǐ you (Note: In Taiwan, 妳 is used to address females, but in mainland China, it is not commonly used. Instead, 你 is used to address both males and females.)
2 电话号码 diànhuàhàomǎ telephone number; phone number
=3 是 shì
  1. to be (followed by substantives only)
  2. correct; right; true
  3. (respectful acknowledgement of a command) very well
  4. (adverb for emphatic assertion)
=3 是 shì variant of 是 shì
=4 多少 duōshǎo
  1. number; amount
  2. somewhat
=4 多少 duōshao
  1. how much?; how many?
  2. (phone number, student ID etc) what number?