Hash partitioning maps data to partitions based on a hashing algorithm that Oracle applies to the partitioning key that you identify. The hashing algorithm evenly distributes rows among partitions, giving partitions approximately the same size.
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Note: You cannot change the hashing algorithms used by partitioning.

Consider, these 4 variables (part_col, no_of_part, bucket_size, prev_2_power)

part_col be candidate partitioning column

no_of_part is the number of partitions we are considering

bucket_size is derived from no_of_part as follows:

if no_of_part is powers of 2(2,4,8,16...) then
bucket_size = no_of_part - 1

else if no_of_part not powers of 2 then
bucket_size = "next higher power of 2" - 1
for eg, if you have 24 no_of_part then (32 -1) = 31

prev_2_power is no_of_part if its a power of 2 number else its previous power of 2. for ex. for 24 partitions, 16 would be prev_2_power

THEN
Partition Number =

case
ora_hash(part_col, bucket_size)+ 1 > no_of_part
then
ora_hash(part_col, bucket_size)+ 1 - prev_2_power
else
ora_hash(part_col, bucket_size)+ 1 /* +1 since bucket start with 0 but partitions start with 1 */
end;