The Calendar.

[giltbrookian]

How many days were lost when the calendar changed from Julian to Gregorian.

[dr b]

Looks like 11 days in Sept 1752 when England adopted it. But earlier in 1582, 10 days were eliminated when the Roman Catholic countries adopted it. Looks like the answer depends on the country or countries referred to as "changing their calendar."

http://www.ancestry.com/learn/library/article. aspx?article=3358

[BigDave44]

If this is a trick question, the answer is none were lost!!

[dr b]

no, they were lost. Children born during that time simply ceased to be. You can look it up.

[Rollo]

Wednesday 2 September 1752 was followed by Thursday September 14 1752, so if your birthday was on one of the "missing" dates then hard luck - no birthday presents for you in 1752.

[giltbrookian]

My thanks to you all.
I intended using it for a quiz that I'm compiling but the answer is too ambivalent so I won't bother.