Follow-up: Bug report: the reconstitution calculator and a rounding edge case

On the subject in the title: Bug report: the reconstitution calculator and a rounding edge case Working notes rather than a conclusion.

Posting the calculation with the inputs, so that somebody can disagree with a step rather than with the answer.

Inputs: 10 mg in 2 mL, target 0.25 mg, U-100 barrel. Working shown below in the order I did it.

I have checked it twice by the same route, which is not the same as checking it twice.

Nothing to add, except that this is the answer I would give if asked.

Maintaining a calculator means checking the arithmetic against hand-worked cases at each review, not checking that it still loads.

The most common input error is entering the vial mass in the concentration field. It produces a plausible number, which is why it survives.

Tools that run entirely in the browser send nothing anywhere, which matters more to some people here than others and is worth stating either way.

Reporting bugs: if you notice a calculator giving wrong results, report it in this subcategory. Bugs are fixed when identified.

Adding the measurement that post #29 says would settle it.

Where a calculator and your own arithmetic disagree, the productive move is to find which step differs rather than to decide which is right.

Post #38 answers the question as asked. The question underneath it is different.

Precision and significant figures: the calculators do not round to match your input precision. If you input values to one decimal place, the output might have more. Use significant figures appropriate to your input precision.

Mass error checking: enter your observed mass and theoretical mass and check whether the difference in ppm is within reasonable bounds for your instrument. Useful sanity check on LC-MS results.