Even then your subjective probability wouldn’t have been exactly 0. You could have put 0.00000000001 or something like that. The instructions didn’t forbid you from using long decimals. Even so, I think it would have been fine to put 0 if your subjective probability really was 0 or you felt like rounding down to it.
You’re assuming the answer I wrote down was an accurate name of a bone.
Even then your subjective probability wouldn’t have been exactly 0. You could have put 0.00000000001 or something like that. The instructions didn’t forbid you from using long decimals. Even so, I think it would have been fine to put 0 if your subjective probability really was 0 or you felt like rounding down to it.