Your Birth Card: The Method

Your Personality card is written into your birth date — you only have to add it up. Mary Greer's method is simple arithmetic, and once you have done it by hand you understand exactly what the app's calculator is doing for you.

The steps

1. Write your birth date as three numbers: the day, the month, and the full four-digit year.
2. Add them together.
3. If the total is larger than 22, add its digits together again.
4. Keep reducing until you land on a number from 1 to 22. That number is your Personality card in the Major Arcana.

A worked example: 7 April 1969

• Day + month + year: 7 + 4 + 1969 = 1980
• 1980 is far bigger than 22, so add its digits: 1 + 9 + 8 + 0 = 18
• 18 is within 1–22, so we stop. Card 18 is The Moon — this person's Personality card.

That is the whole method. Notice that we add the whole year (1969), not just its last two digits, and that we reduce the digits of the total rather than the day, month and year separately. Those two habits keep every birth date on the same footing.

Why 1 to 22?

There are 22 Major Arcana. In this system we count them 1 (The Magician) through 21 (The World), and we give The Fool the number 22 — the card numbered 0 on the deck becomes 22 here, so that every result has a home. If your reduction ever lands on 0, read it as 22, The Fool.

Let the app do it

The calculator in this course takes your birth date and returns your Personality card instantly, then shows the Soul card and Year card that grow from it. Doing the sum by hand once is worth it — it turns a result into something you understand — but you never have to repeat the arithmetic. Enter your date, and the numbers unfold on their own.

The key idea to carry forward: the sum only ever gives you one Personality card. The next lesson shows how that same number opens into a second card — your Soul card — and why Greer reads the two together.