By convention, we normally round 0.5 up to the next whole number, so in fact,
11.5 cm ≤ actual length < 12.5 cm
We call 11.5 the lower bound and 12.5 the upper bound. We can also write the upper bound as
12.4999 . . . . or 12.49
where the dot above the 9 means that it is repeated indefinitely, or recurs.
It is important to see that 12.49 is not the upper bound, as, for example, the length could have been 12.498.
