https://meta.stackexchange.com/a/123521/223820
The OP should take comfort in the fact that they are not the first to have misinterpreted the instructions for gaining the Unsung Hero badge.
An experienced user wrote in 2012, which was edited in 2019, [emphasis in bold mine]
You get the badge when you have at least 10 answers that has been accepted with a score of zero, and those answers are at least 25% of all your accepted answers. For example, if you have 10 accepted answers with a score of zero, and 40 total accepted answers, then you get the badge.
That answer has attracted 84 upvotes, and amazingly no one has noticed the error until…? It's an easy mistake to miss because the number 10, which is a nice round figure, is often used in tests. In fact, many marks at school are given out of 10 or 100, not out of 11 or 101.
Often the instruction “more than 10” can easily be read as "10 or more", especially by non-native speakers, so why mention the number 10 in the first place? Wouldn't it be simpler to say:
"Zero score accepted on at least 11 answers.”
"At least 11 accepted answers without a score”