When the answer is an enthusiastic or reassuring “yes”:
— ¿Me puedes ayudar mañana?
— Cómo no.
— Can you help me tomorrow?
— Of course.
— ¿Conoces un buen lugar para comer?
— Cómo no, hay uno buenísimo aquí cerca.
— Do you know a good place to eat?
— Of course, there’s a great place nearby.
✅ Very common and natural in Mexico.
🎺 A sincere sí, cómo no can sound slightly traditional, polite, or service-oriented.
😏 A sarcastic sí, cómo no is common across generations.
✅ ¿Cómo no? and ¡Cómo no, si…! are also really common and DO NOT sound old-fashioned.
✅ Safe to use with pretty much anyone.
¡Muchísimas gracias por explicar esto!
Professor:
A double negative results in a positive, but a double positive result in a negative does not.
Student:
Yeah, right...