Easiest i could think of was to simplify the numerator to (12-2)^2+(12-1)^2+12^2+(12+1)^2+(12+2)^2 And then it becomes a more manageable 5*12^2 + 2*1^2 + 2*2^2 At which point most folks would find it easy to compute the numerator to 730. Some may even factor out the 5.