yyy wrote:
The convention in math is different. This is the fundamental thing. Not what runners do. Runners have zero (measure) credibility in math
https://en.wikipedia.org/wiki/Null_set
Math does not have a conventional way to approximate times.
Math has choices.
You can generally round to the nearest nth. which is what some here want to do.
You can round up - this is what they do for official track times.
Someone running 9.921 gets credited with running 9.93 while someone running 9.920 gets an official time of 9.92.
You can truncate - call a 3:59.85 mile a 3:59 mile.
Math doesn't care what you do.
What's important is that you pick a convention and stick with it.
If one person rounds to the nearest second while the other truncates, then times cannot be comparable.
If one meet decided 9.921 was 9.93 while another called it a 9.92 it just wouldn't work to keep times comparable.
I am sure chemistry has its conventions for measuring things so that prescription drugs and such can keep a good consistency.
You can't have individual chemists deciding how to measure on their own terms.
Long ago runners have truncated and if you want to talk running, it's best to stick with convention.