Why don't 11, 22 and 33 reduce like the other numbers?
Because Pythagorean numerology treats them as "master numbers," a traditional convention of the system that preserves them even though they have two digits; any other two-digit result, like 29 or 38, keeps getting summed until a single digit remains (29 becomes 11, which then stops for being a master number).
How does the Pythagorean table assign a number to each letter?
It repeats the digits 1 through 9 in sequence across the alphabet: A=1, B=2, C=3... I=9, then starts over at J=1, K=2, and so on through Z=8; since the alphabet has 26 letters and the cycle has 9 numbers, each digit from 1 to 8 appears 3 times and 9 appears 2 times.
Does the Expression number change if I use a nickname instead of my full name?
Yes, because the calculation sums the exact text entered letter by letter; a nickname has fewer letters and a different combination than the birth name, so it almost always produces a different Expression number than the one calculated with the full birth name.
Can two people with different names share the same Life Path number?
The Life Path number does not even use the name, only the reduced birth date; so yes, anyone born on different dates whose reduced digits sum to the same total lands on the same number, the method is a modular sum shared by many people, not a unique identity.