Yes. All six are likely to be incorrect.

Similarly, you could ask a subtle quantum mechanics question to six psychologists, and all six may well give you the same answer. You still should not trust that answer.

The way that LLMs correlate and gather answers is particularly unsuited to mathematics.

Edit: I. Contrast, the average Psychologist is much more prepared to answer a quantum mechanics question, than an average LLM is to answer a math or counting question.

Don't know. I've never asked any of them a maths question.

How costly is it to be wrong? You seem to care enough to ask people on the Internet so it suggests that it's fairly costly. I'd not trust them.

If all 6 got the same answer multiple times, then that means that your query very strongly correlated with that reply in the training data used by all of them. Does that mean it's therefore correct? Well, no. It could mean that there were a bunch of incorrect examples of your query they used to come up with that answer. It could mean that the examples it's working from seem to follow a pattern that your problem fits into, but the correct answer doesn't actually fit that seemingly obvious pattern. And yes, there's a decent chance it could actually be correct. The problem is that the only way to eliminate those other still also likely possibilities is to actually do the problem, at which point asking the LLM accomplished nothing.