The number seven is a magically stable number. Potions that contain seven ingredients are the easiest to synthesize and are usually the first taught to new magic users. The same is true of spells containing seven words or phrases, incantations with seven rhyming couplets, divination with seven objects and so on. The ideal number of digits to cast spells with the hand is seven. The Vodun Xêvisoso is Divine Justice, and is associated with the number seven.
The numbers five and three are both magically significant.
The number three is the number that magical things usually form into if left unchecked. Examples include the Triple Goddess and the triumvirate. The Vodun Jo is associated with the number three because she is always unchecked magic in its natural form. Jo represents things that are difficult to see, the arcana of existence.
The number five is the solid foundation upon which magical things can be soundly built, like a pentagon or pentagram. The Vodun Gû is associated with the number five because of his impeccable skills at artificing, and because of his association with metals that can be used in the wielding of powerful spells.
The number six has symmetry and balance in the natural world, think honeycombs, but it is associated with chaotic, extreme, unstable, or changing magic, like hexes that court chaos, and Lêgba himself whose Veve contains six octograms.
The numbers one and two are not magically insignificant, even if they rely on other things for power.
The number one is associated with the unity of all things, including magic. The Vodun Sakpata identifies with the number one because the mountains of his Disc are considered the bedrock of the Fonlands. Sakpata can and does wield magic, but he is best known for his physical prowess.
The number two represents duality or dichotomy in some cases, but can also represent a union of two things. The union of opposing things is a very strong union. The Vodun Agbe is associated with the number two and is an extremely powerful wielder of magic, but she chooses to rely on her strength, which makes her very formidable.
The number eight, in the Fonlands at least, represents the outside, everything beyond the realm of the living and growing. Even though the Vodun Agê, whose disc contains the growth and death of vegetation, is very well acquainted with death, and the number four, the number eight is associated with death on a larger scale. The number eight is also closely associated with the number thirteen, and both numbers are associated with bad luck.
Ouwo is associated with the number eight.