Make a lookup fail gracefully
A column of #N/A is not a bug — but shipping it to a reader is. Handling the expected failure without hiding the real ones.
The data
| Row number | A | B |
|---|---|---|
| 1 | SKU | Product |
| 2 | A-101 | Wireless Mouse |
| 3 | A-102 | USB-C Dock |
| 4 | B-204 | Monitor 27" |
Your task
Look up SKU "Z-999" in column A and return the product. It is not there — make the formula return "Not in catalogue" instead of an error.
Your formula goes in E2
The checker compares your formula against the accepted answers — it does not run it. The expected result is shown with the solution so you can verify it in your own spreadsheet.
Why this is the right formula
IFNA catches #N/A and nothing else, so if somebody later deletes column B the formula shows #REF! instead of quietly reporting "Not in catalogue" forever. IFERROR would swallow both, which is why it is the wrong reflex around a lookup. XLOOKUP's built-in if_not_found argument is the cleanest of the three, because it never touches errors at all — it just handles the miss.
Try next
Free to use, share and republish — including commercially. Attribution isn't required, but it's what keeps these free to make, and there's one ready to paste below.
Questions
Does this actually run my formula?
No, and it is worth being clear about that. The checker normalises what you type — case, spaces, the semicolon-or-comma separator, dollar-sign anchors — and compares it against every formula that solves the task. The expected result is shown so you can verify it independently in your own spreadsheet.
My formula is different but correct. Will it be marked wrong?
It should not be: each exercise accepts the genuinely different approaches, not one blessed answer. If you find a correct formula that is rejected, the feedback button sends it to us with the page attached.
Do I need an account?
No. There is no signup, no progress tracking and nothing stored — everything happens in your browser.