Different Outputs while counting unique values in a Google Sheet

Question

I have a google sheet which looks like this :

The formula for cell M3 is =COUNTA(UNIQUE(B3:L3)) which outputs the 01/10/00. However the cell B18 is =COUNTA(UNIQUE(B3:B17)) and its output is 15

I wanted to get this count of unique values in the range using the formula but can't figure out the cause of difference of the outputs. Also, the count of unique values in a row should be 11 which is not really reflected in M3 and any changes are not changing the value of the output either.

Answer 1

there is a combo formula for that called COUNTUNIQUE

=COUNTUNIQUE(B3:L3)

Answer 2

The formatting of M3 is probably set to Date and that's converting your number into that date view. Additionally, if you're getting a higher number than you expect in general, double check for trailing spaces that can trick the unique() function.