Check a percentage against its original counts

A percentage needs a clearly defined whole. Before entering a formula, write what you are counting and which items belong in the total.

1. Use a small example you can inspect: twelve completed items out of forty listed items. Confirm that the completed items are included in that same total.
2. Divide the part by the whole. Here, 12 divided by 40 is 0.3, which represents thirty out of every hundred, or 30 percent.
3. In a spreadsheet, calculate the fraction first and apply percentage formatting. Do not multiply by one hundred again when the format already displays the fraction as a percentage.
4. Check the result against a simple estimate: twelve is less than half of forty, so the answer should be below fifty percent.

Label the percentage with its denominator and keep the counts visible. A count of finished tasks does not measure how much effort the remaining tasks require.