If you do it in monthly terms your interest rate is r/12 because there are twelve months in a year.

如果是每月还款那么月利率是r/12,因为一年有12个月

耶鲁公开课 - 金融市场课程节选

where i'm working, you know, twelve hours a day for a couple a months of the year.

一年里好几个月我都是每天工作1２个小时。

为什么是会计学呢？ - SpeakingMax英语口语达人