I don’t know why I’m always confused. I need to write this down so the next time I wouldn’t be.

You may optionally specify the precision/length and scale of the number data type in Oracle i.e. number(9,2).

I remembered it as “leading” & “trailing” (the decimal point) which is INCORRECT.

As discussed here:

column_name NUMBER (precision, scale)

Precision = total number of digits and scale = number of digits to the right of the decimal point.