Solution

160428

First name
Aidan Stimpson
School
Coalbrookdale & Ironbridge C of E Primary School
Country
Age
11

If you notice, once you have done the instructions, your number will always be in the 9 times table - which narrows it down to 9 numbers: 9,18,27,36,45,54,63,72 and 81. Also, every number that is in the 9 times table on the grid has the same symbol.