The idea of lucky numbers is more of a personal belief or superstition, and can vary greatly from person to person. There isn't a universally accepted system for determining them based on astrology.
However, if you are looking for numbers associated with Cancer, you might consider:
* Number 2: Cancers are associated with the element of Water, and number 2 represents duality and balance, which aligns with Water's fluid and adaptable nature.
* Number 4: This number is associated with stability and security, which Cancers value greatly.
* Number 9: Represents sensitivity, intuition, and compassion - qualities strongly tied to the Cancer personality.
Ultimately, the best "lucky number" for a Cancer is the one that feels most meaningful to them individually.