Solution

163841

Problem
Three neighbours Back to problem
First name
leela
School
highgate junior school
Country
England
Age
0

So the answer is a multiple of 3 because I did:
1+2+3= 6 51+52+53=156
2+3+4= 9 10+11+12=33
6+7+8= 21
7+8+9=24
And all of the answers are a multiple of three.