A plan lists a task as “1.30 hours”. Does that mean an hour and thirty minutes, or a decimal number of hours? Before asking an AI tool to add the rows, settle that question. A neat table can hide an ambiguous input.
One hour and thirty minutes is 90 minutes, or 1.5 hours. A decimal value of 1.30 hours is 78 minutes. The two interpretations differ by twelve minutes for just one row.
Convert to minutes before adding
Keep a copy of the original list. Give each duration an explicit unit, such as “90 minutes”, rather than silently interpreting punctuation. If someone else supplied an ambiguous value, ask what they meant.
Try a small example: 30, 60 and 90 minutes should total 180 minutes, or 3 hours. Ask the tool to preserve the original value in one column, show minutes in another, and provide decimal hours separately. You should be able to check every conversion without trusting the final total.
Use the request “Flag unclear units instead of guessing” when preparing the table. That is a useful instruction, but still inspect the output yourself.
Check what the spreadsheet actually stores
A clock time, a duration and a decimal number are different interpretations. Excel’s documentation distinguishes time-formatted results from totals expressed in one unit. Copying a display such as 1:30 into a numeric-hours column is not a reliable conversion method.
Label the final column clearly and check how your spreadsheet handles decimal separators. Recalculate the small example after import. If it changes, fix the import or cell interpretation before applying the same process to the full list.