CarlaRPh_TPA said:

The version of this that has an answer is narrower than the version being asked.

Coming at CarlaRPh_TPA’s question from a different direction. Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the correction. That is slower than asserting, and it is the only version that survives being wrong.

One concrete data point for the thread. One habit that pays for itself: post the method alongside the number. A figure without its method cannot be checked, and an unchecked figure is how this community accumulates folklore.

Following on from CarlaRPh_TPA — and this may be the naive question:

Was that from a primary source or from a summary of one?

VendorMark said:

One habit that pays for itself: post the method alongside the number.

I am going to disagree with the direction of travel here. The thread has converged on the tidiest answer rather than the best-supported one, and those are not the same thing.

Reporting back.

Resolved, and the thing that resolved it was the least interesting suggestion in the thread. Writing that down for the next person who wants the interesting answer.