1. The problem statement, all variables and given/known data prove that 1!+2!+...+n! is not a square if n>=4 2. Relevant equations 3. The attempt at a solution in the previous part I had to prove that a sqare cannot end in 2,3,7,8 and did this by working in mod10. Do you use this to prove the question? I have written n as 10q+r where q,r are rational numbers and r=0,1,2,...,9 but I dont know where to go from here. I would prefer a hint rather than the full solution. Thankyou.