Cause informal seems way more practical than having to subtract in the formal variation Normally, that's the most common way to say it and it doesn't have to do with formality. The substraction is rarely (if ever) used by Mexicans. We only express how long until the next hour comes but this usually happens after the 35 minute mark every five minutes for easier maths. We also use "y" only at the 15 and 30 minute marks to express y cuarto and y media; other than that I don't think it's common but we do use con although it still sounds a little formal: 12:00: Son las doce; son las doce en punto; es mediodía [noon]; es medianoche [midnight] 12:01: Son las doce uno 12:09: Son las doce nueve 12:15: Son las doce y cuarto; son las doce quince 12:25: Son las doce veinticinco 12:30: Son las doce y media; son las doce treinta 12:35: Son las doce treinta y cinco; son veinticinco para la una; faltan veinticinco para la una 12:42: Son las doce cuarenta y dos 12:45: Son cuarto para la una; son las doce cuarenta y cinco; son cuarto para la una; falta un cuarto para la una; faltan quince para la una 12:50: Son las doce cincuenta; son diez para la una; faltan diez para la una More on reddit.com

The question I was supposed to answer was “¿A qué hora es el almuerzo?”. They said it was at 12 pm. So I wrote “El almuerzo es a las doce de la tarde.” But they said it was supposed to be “El almuerzo es a las doce del día.” Shouldn’t both work? I would never use "tarde" for 12 pm. For me "tarde" is always used some time after lunch. The most natural answer here in Spain would be "El almuerzo es a las 12 de la mañana" because we start having lunch after 13pm so we consider 12pm still morning. But technically 12pm is already noon so in other countries "El almuerzo es a las 12 del mediodía" is more correct. This is fine in Spain too and can be used, so you could stick to this answer as the correct one. But I would avoid "tarde" here anyway. On the other one I got wrong, they gave us times and we were supposed to say what time it is. It said 12:00 am. I put “Son las doce de la mañana.” It was corrected as “Son las doce de la noche.” Before this, I thought that de la mañana = anytime in the AM, de la tarde = PM before dark, and de la noche = PM after dark. Is this incorrect? I know that the other ways to say 12 PM and 12 AM are “mediodía” and “medianoche” but why were my answers wrong? I do consider 12 AM night not morning, so I guess de la noche makes sense, however the correct answer for 1:00 AM was “Es la una de la mañana.” Is it not correct to say de la mañana until 1 AM? I think of 1 AM as night as well. You use "de la mañana" after 12 AM but you don't include 12 AM. 12 AM = de la noche 1 AM = de la mañana As a side note. In some countries (Spain, Chile, maybe there are more) we use the 24 hour system and rarely use the AM/PM system when writing. More on reddit.com