Numerology is any belief in divine, mystical or other special relationship between a number and some coinciding events. It has many systems and traditions and beliefs.
Wikipedia does not define specifically Hindu numerology, but still we know that it is a widely accepted practice in India and hence we must define whether it is off-topic or on-topic.
There are some authors which have written about Indian Numerology and it is widely used in India with regard to buying items, registering cars/houses etc. This may not necessarily mean that it is a part of Hinduism though.
Nonetheless, is it off-topic or on-topic?