Find fractions that cannot be cancelled down (resilient fraction).
Prime Subset Sums
Find the number of non-empty subsets of {11, 22, 33,…, 250250250250}, the sum of whose elements is divisible by 250.
Find the number of factors in an enormous factorial.
Determining the value of infinite polynomial series for which the coefficients are Fibonacci numbers.
Investigating isosceles triangle for which the height and base length differ by one.
Finding the maximum remainder when (a − 1)n + (a + 1)n is divided by a2.
Find the number of consecutive integers pairs that have the same number of positive divisors.
Investigating minimal repunits that divide by n.
Finding square sums that are palindromic.