Excel PracticeIFERROR practice
A column of error messages looks broken. A column of deliberate fallbacks looks finished.
What this lesson covers
IFERROR evaluates the first argument and only uses the fallback when that first argument would have failed.
3 exercises in this lesson
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Task 1 · cell E10
Return "n/a" if dividing 10 by C2 fails.
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Task 2 · cell E10
Return "n/a" if SQRT of a negative number fails.
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Task 3 · cell E10
Return 0 if looking up a missing item fails.
Using IFERROR at work
The syntax is IFERROR(value, fallback). Once it is in your hands, the work it replaces is the kind of thing that used to mean scrolling a column and hoping you did not miss a row.
This is lesson 23 of 37. It takes a few minutes, and the exercises are marked the moment you submit rather than at the end.
Where people usually slip
- Ranges drift. Pointing at three cells when the data has six is the single most common cause of a wrong total, and it is invisible because the answer still looks plausible.
- Copying breaks a reference. Relative references shift when a formula is copied. If a value should stay put, lock it with dollar signs.
- The number is right, the method is not. Typing a total by hand produces the right answer once. A formula produces it again when the data changes, which is the actual skill.
How this is marked
Each exercise is checked against the result the formula should produce, and then re-run on a different set of numbers. A hardcoded answer passes the first check and fails the second, so it is rejected. That second pass is the part that makes the practice stick.