SUMPRODUCT(...)

Category: Math and trigonometry

Returns the sum of the products of corresponding array components

SUMPRODUCT(array1, [array2], [array3], ...)

Category: Information

Returns TRUE if the value is text

ISTEXT(value)

0

The ISTEXT() function is used to check if the cell contains text. The result is an arry of TRUE and FALSE that are multiplied with 1 and is summed up by SUMPRODUCT formula.