To confirm that a range of cells all have the same value, you can use a formula based on the COUNTIF function. In the example shown, the formula in C9 is:
=COUNTIF(C5:C8,"<>ok")=0
Note: this formula...

Note: Excel has a built-in data validation rules for dropdown lists. This page explains how to create a custom validation rule when you want to *prevent* a user from entering a value in a list.
To allow only values...

To count positive numbers in a range of cells, you can use the COUNTIF function. In the generic form of the formula (above) rng represents a range of cells that contain numbers.
In the example, the active cell contains...

To count the number of cells that contain text (i.e. not numbers, not errors, not blank), use the COUNTIF function and a wildcard. In the generic form of the formula (above), rng is a range of cells, and "*" is a...

To search an entire worksheet for a value and return a count, you can use a formula based on the COUNTIF function.
In the example shown, the formula in C5 is:
=COUNTIF(Sheet2!1:1048576,C4)
How this formula works...

To test if all values in a range are at least a certain threshold value, you can use the COUNTIF function together with the NOT function. In the example shown, the formula in G5 is:
=NOT(COUNTIF(B5:F5,"<65...

If you want to find out what values in one list are missing from another list, you can use a simple formula based on the COUNTIF function.
The COUNTIF function counts cells that meet supplied criteria, returning the...

One way to track attendance is with simple formulas based on the COUNTIF function. In the example shown, the formula in M5 is:
=COUNTIF(C5:L5,"x")
How this formula works
This formula simply uses COUNTIF...

To count the number of cells equal to a specific values, you can use the COUNTIF function.
In the example shown, G6 contains this formula:
=COUNTIF(D5:D11,"red")
How this formula works
The COUNTIF...

If you want to compare two ranges, and count total matches between the two ranges, you can use a formula that combines the COUNTIF and SUMPRODUCT functions.
Context
Suppose you have a "master" list of some kind, and...

If you need to determine if a range or column contains specific text (a specific substring or partial text), you can use a formula based on the COUNTIF function with wildcards.
In the example shown, the formula in D5...

Note: Excel contains many built-in "presets" for highlighting values with conditional formatting, including a preset to highlight cells that begin with specific text. However, if you want more flexibility, you can use...

To count the number of cells that begin with certain text, you can use the COUNTIF function. In the generic form of the formula (above) rng is a range of cells, txt represents the text that cells should begin with, and...

To count the number of cells that end with specific text, you can use the COUNTIF function. In the generic form of the formula (above) txt represents the text that cells should end with, and "*" is a wildcard matching...

To count matches in entire workbook, you can use a formula based on the COUNTIF and SUMPRODUCT functions. In the example shown, the formula in D5 is:
=SUMPRODUCT(COUNTIF(INDIRECT("'"&sheets&"'!...