Crowds can be smarter than individuals. Especially on questions with historical dates! So how can one person become many (or at least two)? The British Psychological Society Research Digest comes across a suggestion.
The next time you’re asked to estimate a historical date, for example, try doing the following: make your first estimate; then pause and assume your first guess was off the mark. Consider why, then use this new perspective to make a second estimate. Average your two estimates and, chances are, this newly calculated date will be more accurate than your original answer.