If the dot (.) can appear anywhere in the password and the rest are numbers, you can use a custom mask to cover all possible positions. Assuming a password length of 6 (i.e., 5 digits and 1 dot), you can generate the following mask combination:
.? d? d? d? d? d
? d.? d? d? d? d
? d? d.? d? d? d
? d? d? d.? d? d
? d? d? d? d.? d
? d? d? d? d? d.
In hashcat, you can save these masks in a file, such as mask.txt, and then use that file for mask attacks:
hashcat -m <hash-type> -a 3 hash.txt -m 3 mask.txt
-a 3: mask attack mode.
mask.txt: The file containing each mask combination.
-i: Optional parameter for incremental mode, which can be added if the password length is not fixed.
<hash-type>: Your hash type number.
This method ensures that all number combinations containing a dot are covered.