Calculation method
The calculator adds every digit in the selected birth date. A total such as 29 becomes 2 + 9 = 11. A total such as 28 becomes 2 + 8 = 10, then 1 + 0 = 1.
- Add all date digits
- Repeat until 1 to 9
- Keep 11, 22, and 33
- Show every reduction step