Posted by Anonymous on .
If the sum of 1! + 2! + 3! + 4! + ... + 49! + 50! is divided by 15, what is the remainder?

8th grade math 
drwls,
Every number above 14! will have zero remainder, since 15 is one of its factors. So, ask the same question about 1! + 2! + 3! + ...14!
All terms greater than 5! have both 3 and 5 as factors, so ask the same question about 1! + 2! + 3! + 4!
That sum is 33. Dividing that by 15 gives 3 with a remainder of 3.
The remainer of the full sum up to 50!divided by 15 will also be 3.