Administration and Executive AssistantTier 345 minintermediate

Error Handling That Teaches Rather Than Hides

Deal with missing and bad data in a way the next reader can see and fix.

What you will learn

• Tell the difference between an error, a blank, and text that looks like a number
• Explain why IFERROR(..., 0) can make a total or average wrong without any warning
• Use IFNA, ISNUMBER and explicit labels to flag the specific problem
• Exclude flagged rows from summary statistics deliberately

Excel skills

IFNA, IFERROR, ISNUMBER, ISBLANK, AVERAGE · Honest Error Handling

The task

The board wants our average gross margin. Margin % is (Selling Price - Cost Price) / Selling Price. Some products have no cost price yet: a few are blank, and one says "TBC". Those products must show "Missing cost" in the Margin column, must not count towards the average, and I need to know how many there are.

You work in a real spreadsheet in your browser, and your answer is checked against hidden traps the moment you submit.

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