The LLM indicated an approximate value, and I thought that precision wasn't that important in the strategy?

In this case it was close, but only by coincidence. It could equally have been off by a mile, as long as the answer sounded statistically plausible. If it doesn't know what book value per share is/was or what that means, which of course it doesn't, it's not something you'd trust to do any research or calculation that matters.

For fun, I gave the response you received to a different LLM and asked if it was accurate. It responded that no, it was close, but not accurate, and then gave four different book values per B share, all wrong by a bit. (Perhaps by using average shares outstanding during the period rather than shares outstanding at the date of the statements? --admittedly that would be a fairly subtle error that even a somewhat attentive human analyst might make)

Jim