In this example, the goal is to count numbers in the range B5:B15 (named data) that begin with the numbers shown in column D. You would think this would be a good problem to solve with the COUNTIF function but for reasons explained below, COUNTIF won't work. Instead, you can use the SUMPRODUCT and Boolean logic. See below for a full explanation.
The COUNTIF function returns the count of cells that meet one or more criteria, and supports logical operators (>,<,<>,=) and wildcards (*,?) for partial matching. You would think you could use the COUNTIF function with the asterisk wildcard (*) like this:
=COUNTIF(data,"25*") // returns 0
The problem however is using any wildcard character means criteria must be handled as a text value in double quotes ("") whereas the values in column B are TRUE numbers. As a result, COUNTIF will never find a matching number and the result will always be zero. You might also think of this trick to coerce the numbers in data to text by concatenating an empty string ("") to the range like this:
=COUNTIF(data&"","25*") // throws error
But this will throw an error, because COUNTIF is in a group of eight functions that require an actual range for range arguments. In other words, you can't use an array operation in place of a range argument.
=SUMPRODUCT(--(LEFT(data,2)="25")) // returns 5
Working from the inside out, the LEFT function is used to check all numbers in data like this:
Because we give LEFT 11 numbers in the range B5:B15, LEFT returns an array with 11 results:
We then compare each value to "25" to force a TRUE or FALSE result. Note that LEFT automatically converts the numbers to text, so we use the text value "25" for the comparison. The result is an array of TRUE and FALSE values:
In this array, TRUE values correspond to numbers that begin with "25" and FALSE values represent numbers that don't. We want to count these results, but first we need to convert the TRUE and FALSE values to 1s and 0s. To do this, we use a double negative (--).
The resulting array contains only 1s and 0s and is delivered directly to the SUMPRODUCT function:
With only a single array to process, SUMPRODUCT sums the items in the array and returns 5 as result. In this formula, note we are hardcoding the value "25" and the length of 2. To adapt the formula for the worksheet shown, where the numbers we want to count appear in column D, we use the LEN function and a reference to cell D5 like this:
The LEN function returns the number of characters in D5. This makes the formula more generic so it will support numbers of different lengths. Also note that the numbers in column D are entered as text values, since the result from LEFT will also be text. You can avoid this requirement by adapting the formula to coerce the value in D5 to text:
Here we concatenate an empty string ("") to the D5, which converts any number to text. This version of the formula will work when there are numbers in column D, or text values.