Summary
COUNT is not as straightforward as it might look. Many people think it counts the number of cells in a range, or the number of populated cells. But it doesn't. Instead, it counts the number of cells in a range that contain a numeric value. This will include dates, percentages etc. as well as your bog-standard numbers.
If the cells in your range contain the values 1, 2, 3, Y and 4, then the function will return the value 4, ignoring the Y. Blank cells will be similarly ignored. Similarly, it will ignore logical values (i.e. those that contain a TRUE/FALSE value). But cells containing a zero will be included in the count.
Syntax
=COUNT(Range)
Range can be made up of a single range or a set of distinct ranges. If you're using a set of distinct ranges, they should be separated with commas.
Examples
=COUNT(A1:Q20): this will count the number of numeric cells between columns A and Q, in rows 1 through 20
=COUNT(A1,C5,D12,D15:D20): this will count the number of numeric cells the ranges specified

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How do you count text? I did a 6 week/24 different position schedule spreadsheet for my supervisor and when he's made up the schedule there have been a lot of mistakes-duplicate shifts scheduled or shifts unscheduled. I want to make a small spreadsheet at the bottom of the schedule that would tell him if there was any missing/duplicated shifts for each day of the schedule. I'm a novice at this, but I thought a counting formula might work, but I don't know how it works with text. Is this a dumb idea? Any suggestions?