# Dr. Miller's daughter was born 421 months ago. Answer the two questions using modular arithmetic

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?

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Yes you do, since you know that there are twelve months in a year... – J. M. Dec 9 '11 at 0:20
You might want to consider going through your older questions and accepting those you've found helpful, by the way; that red "0%" is a bit distracting... – J. M. Dec 9 '11 at 0:22

Exactly. It is now December=11 (if January=0). You calculate $421 \pmod {12}$ and subtract to see what month she was born in.