The Chaldean system gives each letter a value from 1 to 8. The number 9 is not given to any letter. For example A, I, J, Q and Y are 1; B, K and R are 2; and F and P are 8.
To find a name number, write the value of every letter, add them to get a compound number, then add the digits of that total until one digit remains.
Because spelling changes the letters, different spellings can give different numbers. That is a feature of the method, not proof that one spelling is better for you. There is no scientific evidence that changing a spelling changes luck or life outcomes.