Also wrong. There wasn't year 0. The first year after 1 BC …

Also wrong.
There wasn't year 0. The first year after 1 BC was 1 AD.
1-2 1 year
2-3 2
3-4 3
4-5 4
5-6 5
6-7 6
7-8 7
8-9 8
9-10 9
10-11 10 years
and so on…