a) in which month was she born? b) how old is she?
This question has to be used by modular arithmetic...do you use mod 12 to figure out what month she was born?
a) in which month was she born? b) how old is she?
This question has to be used by modular arithmetic...do you use mod 12 to figure out what month she was born?
Exactly. It is now December=11 (if January=0). You calculate $421 \pmod {12}$ and subtract to see what month she was born in.