Solution

156425

First name
Rowan
School
American School in London
Country
Age
9
Email address
rowanh4437@gmail.com

the number is 64. Here is what I did:
I Started with the first clue and singled out the numbers that fit that certain clue, then made a mental not e of the ones that did fit the clue. I continued with that until I only had one number that still fit the clue. The number that I got was 64. I double cheked that by acually doing it and crossing out the ones that don't fit.