When working with data, it is common to have duplicate values in a range. Please check here to count the number of unique values in a range, or here to count cells without duplicates.
To calculate the numbers only with duplicates, you can use the unique count minus the number of cells without duplicates.
Question: How many numbers are duplicates in column C?
=SUMPRODUCT(1/COUNTIF(C2:C12, C2:C12)) – SUMPRODUCT(–(COUNTIF(C2:C12, C2:C12)=1))
=SUMPRODUCT(1/COUNTIF(C2:C12, C2:C12)) – SUMPRODUCT((COUNTIF(C2:C12, C2:C12)=1)*1)
The result returns 3, so three numbers are duplicates in column C.
Explanation:
- Step 1: SUMPRODUCT(1/COUNTIF(C2:C12, C2:C12)): To find the number of unique values in the range;
- Step 2: SUMPRODUCT((COUNTIF(C2:C12, C2:C12)=1)*1): To find the number of values without duplicates;
- Step 3: The difference will be the number of cells with duplicate values in the range.
To figure out the number of cells with duplicate values, you can use the following formula:
=COUNT(C2:C12) – SUMPRODUCT(–(COUNTIF(C2:C12, C2:C12)=1))
=COUNT(C2:C12) – SUMPRODUCT((COUNTIF(C2:C12, C2:C12)=1)*1)
The result returns 6, so six cells are duplicates.
Notes: The SUMPRODUCT Function
The SUMPRODUCT function adds all the multiplication results for all arrays.
Formula:
=SUMPRODUCT(array1, [array2], …)
Explanations:
– Array1 is required; the first array is to multiply and then add.
– Array2 is optional; the second array is to multiply and then add.