Cual es tu telefono = What is your telephone number
What is your phone number?
"What's your telephone number?" How DO you answer that?
Cual es tu nacionalidad means "what is your nationality". So you would reply with your nationality ("Mi nacionalidad es....)
cual es tu means 'what is your....' (informal)cual es su means 'what is your....' (formal)
cual es tu apellido means what is your surname so you would with respond with your last name.
Which is your sport.
Mi nombre es...
Cual es el poblacion de tu pais means What is the population of your country
its writen as: cual es tu numero. it means what is your number
Which is your direction?
What is your birthday?
No tengo un apellido, soy un asistente virtual. Puedes llamarme simplemente asistente. ¿En qué más puedo ayudarte hoy?