# How to Count Cells on A Day

The SUMPRODUCT function is to return the sum of the products of corresponding ranges or arrays. It can also count the cells in a certain yeara month, or a day. The following formula is to figure out the number of cells in a day (e.g., the ninth day in a month).

Example: You are working with a dataset with the first name in column A, the last name in column B, and the DOB (date of birth) in column C.

Formula 1: To count the number of people that were born on the second day

=SUMPRODUCT(--(DAY(C2:C12)=2))

• DAY(C2:C12)=2: if DOB is on the second, it returns true, otherwise false;
• The double hyphens (--) convert true into 1, and false into 0;
• The SUMPRODUCT returns the sum of the products of the array.

The result returns 3, and three people were born on the second day.

Formula 2: To count the number of people that were born on the 10th

=SUMPRODUCT(--(DAY(C2:C12)=10))

The result returns 2, and two people were born on the 10th.

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.