I see two distinct problems that were found:

-As Leslie shared: the "2 ml is .5 tsp" choice of approximation (instead of something closer like "2 ml is .4 tsp", which is also equivalent to the "5 ml is 1 tsp" approximation [although more precisely, "4.92892 ml is 1 tsp]"). It's clear the "2 ml is .5 tsp" choice of approximation also yielded the 24 servings number, since 48 ml=(24)*2 ml.

-The reader who shared this topic only got 16 servings worth, or (assuming .5 tsp = 1 serving) 8 tsp worth of the MiO water enhancer. With 1.62 fluid oz being approximately 9.72 tsp (or 19.44 ~ 19.5 servings, or more than 19 servings) [and that's a lower approximation, as 48 ml = 9.73844 tsp, or ~9.73 or ~9.74], what happened to the extra 1.72 ~ 1.5 tsp (about 3 or more servings)? Perhaps they were still in the bottle, in tough-to-squeeze-out corners, or no?