sum of reciprocals

. Find the sum of reciprocals of all positive divisors of 360.

1, 2, 3, 4, 5

Consider all the 5-digit numbers containing each of the digits 1, 2, 3, 4, 5 
exactly once, and not divisible by 6. Find the sum of all these numbers. 

100 CHOCOLATES

In how many ways can you distribute 100 identical chocolates among

10 children so that the number of chocolates everyone gets is a multiple of 3, 

allowing some chocolates to be undistributed?

 [In solving this problem, you should take 0 to be a multiple of 3.]

Prime Gap Grows After Decades-Long Lull

PRIME GAPS