The answer is that the function does not remove commas and currency symbols before conversion, which causes the null returns. When Power Query attempts to convert a value like '$ 1,234.56' using Number.From or Number.FromText, the dollar sign, spaces, and comma are not recognized as valid numeric characters, so the conversion fails and returns null—even though the text appears to be a valid number. This scenario is a common trap on the Microsoft Power BI Data Analyst PL-300 exam, testing your understanding of how Power Query handles "numbers stored as text" and the importance of cleaning data before transformation. The key insight is that a try...otherwise block only catches errors; it does not sanitize the input, so the conversion still fails silently. A useful memory tip: "Clean before you convert—strip symbols and spaces, or null will be your reward."
PL-300 Prepare the data Practice Question
This PL-300 practice question tests your understanding of prepare the data. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
Refer to the exhibit. The following Power Query M function is defined:
(value as any) as nullable number =>
try Number.From(Text.Replace(Text.Clean(value), " ", ""))
otherwise null
You are cleaning a column that contains numbers stored as text, with occasional leading/trailing spaces and currency symbols. You apply the function above to the column. However, some rows return null even though the original text appears to be a valid number, such as '$ 1,234.56'. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Refer to the exhibit. The following Power Query M function is defined:
(value as any) as nullable number =>
try Number.From(Text.Replace(Text.Clean(value), " ", ""))
otherwise null
A
The try...otherwise block is not catching parsing errors.
Why wrong: The try...otherwise does catch errors; the function returns null as intended, but the root cause is that the input still contains invalid characters.
B
Text.Clean removes necessary decimal separators.
Why wrong: Text.Clean removes non-printable characters, not decimal separators.
C
The function is applied to the wrong data type column.
Why wrong: The function expects text, and the column is text; that is not the issue.
D
The function does not remove commas and currency symbols before conversion.
The function only removes spaces and cleans non-printable characters. Commas and '$' remain, causing Number.From to fail.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The function does not remove commas and currency symbols before conversion.
Option D is correct because the function shown (likely a custom M function or Power Query transformation) does not strip commas and currency symbols before attempting conversion. When the input '$ 1,234.56' is passed directly to a number conversion like Number.From or Number.FromText, the presence of the dollar sign, spaces, and comma causes the conversion to fail, returning null. The try...otherwise block only catches errors but does not clean the text, so the conversion still fails silently.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The try...otherwise block is not catching parsing errors.
Why it's wrong here
The try...otherwise does catch errors; the function returns null as intended, but the root cause is that the input still contains invalid characters.
✗
Text.Clean removes necessary decimal separators.
Why it's wrong here
Text.Clean removes non-printable characters, not decimal separators.
✗
The function is applied to the wrong data type column.
Why it's wrong here
The function expects text, and the column is text; that is not the issue.
✓
The function does not remove commas and currency symbols before conversion.
Why this is correct
The function only removes spaces and cleans non-printable characters. Commas and '$' remain, causing Number.From to fail.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the try...otherwise block will handle all conversion issues, but they overlook that the conversion itself must first succeed on a clean string—the error handling only catches failures, it does not fix malformed input.
Detailed technical explanation
How to think about this question
In Power Query M, Number.FromText expects a string that contains only digits, an optional sign, and a decimal separator (based on locale). Any extraneous characters like currency symbols, spaces, or thousands separators cause an error. The try...otherwise pattern in M returns null when an error occurs, but it does not transform the input; proper cleansing requires steps like Text.Remove to strip non-numeric characters and Text.Replace to remove commas before conversion.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Prepare the data — This question tests Prepare the data — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The function does not remove commas and currency symbols before conversion. — Option D is correct because the function shown (likely a custom M function or Power Query transformation) does not strip commas and currency symbols before attempting conversion. When the input '$ 1,234.56' is passed directly to a number conversion like Number.From or Number.FromText, the presence of the dollar sign, spaces, and comma causes the conversion to fail, returning null. The try...otherwise block only catches errors but does not clean the text, so the conversion still fails silently.
What should I do if I get this PL-300 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PL-300 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PL-300 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.