You have been invited to a fundraising gala and decide that this black-tie event demands an elegant white Italian shirt — just like the one you got years ago for your wedding.
When you find and bravely try the wedding shirt (size 16) on, you and your wife notice that the collar suffocates you — you absolutely need 1/4″ more space everywhere in-between your neck and the collar all around your neck.
So you’ll need a new shirt.
Brain teaser: What size shirt do you need to buy?
(Puzzle answer is below. Please try to solve it before checking out the answer)
PS: In case you don’t know, shirt size 16 means that a tape wrapped around your neck and two fingers positioned flat upfront will measure 16 inches. 
Maria Lando (aka TheMathMom) illuminates and demystifies mathematics for adults, describing its fun use in everyday life. TheMathMom has been featured in multiple media outlets including The Boston Globe, The Jewish Advocate, and Redbook Magazine. Learn more at TheMathMom.com.
Puzzle answer
Yes, math can come handy in the dressing room, so let’s refresh our geometry. A shirt collar is almost circular, and as you probably remember circle circumference = 2 x Pi x Radius. Shirt size 16 means that a tape wrapped around your neck and two fingers positioned flat upfront will measure 16 inches.
At the time of your wedding: 2 x Pi x Radius of your neck = 16.
But now: 2 x Pi x new Radius of your neck =
2 x Pi x (wedding Radius of your neck + 1/4) =
2 x Pi x wedding Radius of your neck + 2 x Pi x 1/4 =
16 + Pi/2 =
16 + 3.14/2 =
17.57 (approx).
So, you are more around size 17.5 now.
Happy shopping!
