20Celebrate The End Of Counting Months, Your Child Is Two Years Old - Period
How old is your baby? Two - bam. No more twenty-one months nonsense and stumbling to remember what month it is; that's for babies, and you no longer have one of those. You've got a full-on toddler human with a real, live, prime number as their age.
It might be fun
to mess with people a little, though, and keep it going. Thirty-one months would technically be a correct answer, and you can watch people's faces as they attempt to do some quick division in their heads.
One of my kids is fifteen. Perhaps the next time someone asks me his age, I'll say "185 months."