This problem was very accessible and all the solutions received were neat and concise and similar to the one below.
Congratulations to Ashley of Bentley Park College, Sana, Jenny,
Chris and Rosion of Madras College, St. Andrews, as well as
Mary of Birchwood High School, Andrei of School 205 Bucharest, Chen of the Chineses High School, Singapore.
In this 903-digit number, the first 900 digits comprise 1, 2, 3, 4, 5 as a sequence of recurring digits with the last three digits being being 1,2 and 3.
Thus, the sum of all the digits = (900/5) x (1+2+3+4+5)+1+2+3 = 180x15+6 = 2706