Uhh...what?

See, this was why Kate didn't like Arithmancy. There was no wild guessing here. In most other subjects, you could provide an opinion or give a thought. In Arithmancy, though, you had to arrive at a certain number, and there was no other way around that. Kate copied the numbers onto her parchment.

441,315,565,100

Kate completed the work the best way she knew how.

4 + 4 + 1 = 9
3 + 1 + 5 = 9
5 + 6 + 5 = 16 ... 1 + 6 = 7
1 + 0 + 0 = 1

9 + 9 + 7 + 1 = 26
2 + 6 = 8

8: Authority, finances, business, success, material wealth, self-mastery, complex thought/reasoning, fluidity, movement

Sooo..., had she done the right thing? What was the tried and true method anyway?