Masculine numbers symbolize strength, concentration, and the ability to lead, and they are associated with male planets. Feminine numbers represent dispersion, adaptability, and the ability to please, and are connected with female planets. In Chaldean numerology, the numbers 1, 3, and 9 are considered the most masculine. Cheiro said of them that they are associated with martial music, thereby indirectly revealing their masculine nature.

The number 1 is the male aspect of the Sun and represents concentration, power, and leadership. It therefore possesses all the attributes of masculinity. At the same time, however, the number 1 encompasses all that exists, and thus it also contains certain feminine traits within itself. The number 9 is the number of warriors and is therefore fundamentally masculine. Yet in the lunar system, the number 9 represents the second day of the second week and is under the sign of the Moon. In the background, this number too contains some feminine qualities.

What about the number 3? The number 3 represents expansive Jupiter, which is a masculine number. In the lunar system, the number 3 corresponds to Tuesday and Mars. Warlike Mars, alongside Jupiter, is another masculine planet. Based on the above criteria, the number 3 can indeed be defined as the most masculine number.

However, one should be cautious, as there may be other criteria that ought to be taken into account. For ordinary numerological practice, it is entirely sufficient to classify the numbers 1, 3, and 9 as masculine.