Explanation
In this example, the goal is to count test scores in column C that are less than 75. The simplest way to do this is with the COUNTIF function, which takes two arguments, range and criteria:
=COUNTIF(range,criteria)
The test scores in the range C5:C16 and we want to count scores less than 75, so we configure COUNTIF like this:
=COUNTIF(C5:C16,"<75") // returns 1
Since there is only one score in C5:C16 that is less than 75, COUNTIF returns 1 as a result. Notice that criteria is given as a text value in double quotes (""). This is a requirement of the COUNTIF function which is in a group of eight functions that use a special syntax for criteria. In this syntax, logical operators are joined with numeric values and provided as text.
Less than or equal to
To count cells that are less than or equal to, adjust the formula to use "<=" instead of "<". In the example shown, the formula in F6 is:
=COUNTIF(C5:C16,"<=75") // returns 2
Here, COUNTIF returns 2 since there are two scores in C5:C16 less than or equal to 75.
Value in another cell
To adjust the formula to use a value in another cell as part of the criteria, you can concatenate the logical operator to the cell reference with the ampersand (&) operator like this:
=COUNTIF(range,"<"&A1)
For example, with 75 in cell A1, the criteria will be "<=75" after concatenation:
=COUNTIF(range,"<="&A1)
=COUNTIF(range,"<=75")
=2
The result will again be 2. If the value in A1 is changed to a different number, COUNTIF will return a new result.
COUNTIFS function
The COUNTIFS function is designed to handle multiple criteria, but can be used just like the COUNTIF function in this example:
=COUNTIFS(C5:C16,"<75") // returns 1
=COUNTIFS(C5:C16,"<=75") // returns 2