Regarding 53 being a prime, you can't just do some naive Bayesian mathematics on some real valued probability of 53 being a prime because that probability would be heavily correlated with uncertainty about every other number and every other mathematical operation, including conversion from decimal notation to other representation, internally done mathematics in visual character recognition, and so on. Such probability is entirely meaningless. One could speak of probability of (53 is a prime | mathematics is not completely wrong), that would be a number very close to 1 (due to repeat testing).