Solution

24287

First name
Lingkesh
School
Wilsons
Country
Age
12

18=5+6+7
21=6+7+8
24=7+8+9
27=8+9+10
I think that this is conclusive evidence that multiples of 3 have three consecutive numbers added together to make the number. Also a pattern has emerged that with the previous multiple of three, the second number is the first number for the next multiple of three. Also if you divide the multiple of 3 by 3 you always get the middle number in the consecutive pattern. For example 18 divide by 3 is 6 and 27 divide by 3 is 9.