Why numbers are the shortcut
The forty numbered Minor Arcana cards are the part of the deck beginners find hardest, and the usual approach is to memorise forty separate meanings. There is a much shorter route. Each card is a number in a suit, the number supplies an abstract quality and the suit supplies the arena, and combining them produces a reading that is close to the standard meaning almost every time.
Ten numbers and four suits replaces forty meanings, and the structure generalises: once you know that fives disrupt, you know something true about all four fives before you have learned any of them individually.
Ace through Five
Aces are the root: the pure form of the suit, a beginning, something offered but not yet acted on. Twos are duality and balance: a choice, a partnership, two things held against each other. Threes are the first expression outward: growth, collaboration, something becoming visible to other people.
Fours are stability, and stability read either way: consolidation when it is working, stagnation when it has gone on too long. Fives disrupt. Every five in the deck describes a loss of the fours' equilibrium: conflict, scarcity, grief, or upheaval, depending on the suit.
Six through Ten
Sixes restore. After the fives break something, sixes are recovery, help arriving, or a return to balance on new terms. Sevens challenge again, and more subtly than fives: sevens are about perseverance, illusion, defence, and assessment rather than open disruption.
Eights are movement and mastery: momentum, skill, or leaving. Nines are the near-complete state, which in tarot is frequently uncomfortable, the last stretch, held alone. Tens complete, and completion carries the weight of everything that came before it, which is why the Ten of Cups is fulfilment and the Ten of Swords is the end of the line.
Combining number and suit
Wands are fire (drive, ambition, action. Cups are water) emotion, relationship, intuition. Swords are air (thought, truth, conflict. Pentacles are earth) work, money, the material world. Put a number against a suit and you have a reading.
Five plus Cups is disruption in the arena of feeling, which lands close to the standard reading of grief and loss. Eight plus Pentacles is momentum and skill in the material arena, which is the apprentice at work. Nine plus Swords is the near-complete state in the arena of thought, held alone at night. The method is not a rough approximation. It is where the meanings came from.
Numbers in the Major Arcana
The Majors carry numbers too, and the same qualities echo, though less reliably. Card 1, The Magician, is the Aces' beginning at archetypal scale. Card 5, The Hierophant, and card 15, The Devil, both concern structures that hold people in place. Card 10, Wheel of Fortune, is completion and the turn into a new cycle.
Some readers also reduce Major numbers to a root (15 reduces to 6, 19 to 1) and read the pair together. This is a legitimate technique and it is considerably less consistent than the Minor Arcana numbering, so treat it as a secondary lens rather than a system.