rule of twelfths
approximation to a sine curve used as a rule of thumb for estimating a changing quantity where both the quantity and the steps are easily divisible by 12
en-GB/ˈɹuːl əv ˈtwɛlfθs/
en-US/ˈɹul ʌv ˈtwɛlfθs/
approximation to a sine curve used as a rule of thumb for estimating a changing quantity where both the quantity and the steps are easily divisible by 12