Removing duplicates in Google Sheets - Practice Problems & Coding Challenges

Challenge - 5 Problems

📊 Formula Result

intermediate

Removing duplicates with UNIQUE function

You have a list of names in cells A1:A6:

John
Mary
John
Anna
Mary
Tom

Which formula in cell B1 will return the list without duplicates?

A =SORT(A1:A6, TRUE)

B =REMOVE_DUPLICATES(A1:A6)

C =UNIQUE(A1:A6)

D =FILTER(A1:A6, COUNTIF(A1:A6, A1:A6)=1)

💡 Hint

Use the function that extracts unique values from a range.

The UNIQUE function returns only unique values from the range, removing duplicates. REMOVE_DUPLICATES is not a valid function. FILTER with COUNTIF=1 returns only values that appear once, excluding duplicates that appear multiple times. SORT just sorts the list but does not remove duplicates.

❓ Function Choice

intermediate

Choose the correct function to remove duplicates

You want to remove duplicate entries from a list in Google Sheets. Which function should you use?

A DISTINCT()

B REMOVE_DUPLICATES()

C FILTER()

D UNIQUE()

💡 Hint

Think about the function that returns unique values.

UNIQUE() is the correct function to remove duplicates by returning unique values. REMOVE_DUPLICATES() and DISTINCT() do not exist in Google Sheets. FILTER() is used to filter data but does not remove duplicates by itself.

🎯 Scenario

advanced

Removing duplicates but keeping the first occurrence only

You have a list of product IDs in column A with duplicates. You want to create a list in column B that keeps only the first occurrence of each product ID, preserving the original order. Which formula should you use in B1?

A =UNIQUE(A1:A100)

B =SORT(UNIQUE(A1:A100))

C =FILTER(A1:A100, MATCH(A1:A100, A1:A100, 0)=ROW(A1:A100)-ROW(A1)+1)

D =ARRAYFORMULA(IF(COUNTIF(A$1:A1, A1:A100)=1, A1:A100, ""))

💡 Hint

UNIQUE preserves the first occurrence and order by default.

UNIQUE returns the first occurrence of each value in the order they appear. SORT would reorder the list alphabetically or numerically. FILTER with MATCH and ROW is complex and unnecessary here. ARRAYFORMULA with COUNTIF returns blanks for duplicates but leaves gaps.

📊 Formula Result

advanced

Removing duplicates with multiple columns

You have data in columns A and B:

A1:B5
1, Apple
2, Banana
1, Apple
3, Cherry
2, Banana

Which formula in D1 will return unique rows based on both columns?

A =UNIQUE(A1:B5)

B =UNIQUE(A1:A5 & B1:B5)

C =FILTER(A1:B5, COUNTIF(A1:A5, A1:A5)=1)

D =SORT(UNIQUE(A1:B5))

💡 Hint

UNIQUE works on multiple columns to remove duplicate rows.

UNIQUE applied to a range with multiple columns removes duplicate rows considering all columns. Option A concatenates columns but returns a single column of text, not rows. FILTER with COUNTIF only checks column A and does not remove duplicates properly. SORT just sorts the unique rows but does not affect duplicates removal.

❓ data_analysis

expert

Count unique values ignoring blanks

You have a list of values in A1:A10 with some duplicates and blank cells:

Apple
Banana

Apple
Cherry
Banana

Cherry
Durian
Apple

Which formula correctly counts the number of unique non-blank values?

A =COUNTA(UNIQUE(A1:A10))

B =COUNTUNIQUE(FILTER(A1:A10, A1:A10<>""))

C =COUNTUNIQUE(A1:A10)

D =COUNTA(UNIQUE(FILTER(A1:A10, A1:A10<>"")))

💡 Hint

COUNTUNIQUE counts unique values; FILTER removes blanks.

COUNTUNIQUE counts unique values but includes blanks if present. FILTER removes blank cells before counting unique values. COUNTA counts non-blank cells but does not count unique values correctly when used with UNIQUE. Option B counts unique including blanks, so it is incorrect.