Cavenagh: Happy new year all
"Decade starts on January 1, 2021" lol
I suppose when you were born, your age was 1
No, but the calendar we use started on year 1, not year 0. A person born on Jan 1, 1980 would turn 1 on Jan 1, 1981. At the culmination of his 10th year he would turn 10, on Jan 1, 1990. However, there was no year 0, so a person born on Jan 1, 0001, would turn 1 at the culmination of their first year, on Jan 1, 0002. On Jan 1, 0010, they would turn 9. So their decade would not turn over until 0011. Where did we lose a year that subsequent decades would start on the 0 instead of the 1?
EDIT: Or in simpler terms, the first year is 1. 1 + 10 is 11, not 10. 11 + 10 is 21, not 20.