Created attachment 123699 [details] document demonstrating wrong behaviour Hi! During the trial and error I found that something is wrong with the construct: =SUM(IF(MONTH($A$2:$A$366)=1;$B$2:$B$366;0)) I have the dates from the 1st of Jan to 31 of Dec, I can't get the right results (for the test - the right count of the days - the construct sums everything in the range for the month value=1, for other values the result is zero) - see attachment. Janis
for unknown reasons Ctrl+Shift+Enter does not convert the formula to array - found unintentionally exploring Function wizard (v. 5.0.4, Slack 14.1-64)
If you are going to convert in array the formula, you need first to change something before use Ctrl+Shift+Enter, like add an space to the end. OTOH, in many array formulas it's easy to use SUMPRODUCT() function because it is an array function, and you don't need the Ctrl+Shift+Enter.