How is my crew's Masters age category worked out?

Under Rules of Rowing 4-104.1(d)(2)-(3):

• The category comes from the average age of the rowers, rounded down to a whole number.
• Each rower's age is their age on December 31 of the current year.
• The coxswain's age doesn't count.
• Individual rowers don't have to fall inside the category, as long as every rower is a Master and the crew's average fits.
• A crew can race in a younger category than its average, but never an older one.

Example: a four whose rowers will be 38, 45, 52 and 61 on December 31 averages 49.0, which is category C (43-49). That crew could also enter B, A or AA, but not D.