Write the remainder obtained when 1! + 2! + 3! + ...+ 200! is divided by 14.
We can see, from 7! onwards the terms are divisible by 14.
∵7!=7×6×5×4×3×2×1
=(7×2)×6×5×4×3
=14×360
So, we should consider up to 6! term to obtain the remainder.
Now,
1! + 2! + 3! + 4! + 5! + 6!
= 1 + 2 + 6 + 24 + 120 + 720
= 873
On dividing 873 by 14, we get 5 as remainder.
∵14×62=868
and 873-868=5