mowaliii
一 have tow pronunciations, it's yi as in 一位朋友，一只猫等。 or yāo as in 九一一 which is jiuyaoyao ..
It pronounced yāo for clarity when spelling numbers digit by digit.
hope my explanation help you to understand it, I myself had a lot of struggling with that character.
Posted on: Messing Up The Date
September 18, 2017 at 3:00 PM一 have tow pronunciations, it's yi as in 一位朋友，一只猫等。 or yāo as in 九一一 which is jiuyaoyao ..
It pronounced yāo for clarity when spelling numbers digit by digit.
hope my explanation help you to understand it, I myself had a lot of struggling with that character.