Digit factorials: Find the Sum of All the Curious Numbers
145 is a curious number, as 1! + 4! + 5! = 1 + 24 + 120 = 145. Find the sum of all numbers which are equal to …
Computing the Longest Recurring Cycle in its Decimal Fraction Part
A unit fraction contains 1 in the numerator. The decimal representation of the unit fractions with denominators 2 to 10 are given: 1/2 = 0.5 1/3 = 0.(3) 1/4 …
How to Use Priority Queue in Java or C++ to Compute Last Stone Weight?
We have a collection of stones, each stone has a positive integer weight. Each turn, we choose the two heaviest stones and smash them together. Suppose the stones have …
How Many Squares/Rectangles Does a Rubik Cube Have?
A Rubik cube usually have 6 sides. Take 3×3 rubik cube for example, each side has 9 little squares (1×1), 4 medium squares (2×2) and 1 big square (3×3). …
Find the 10001st Prime Number
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13. What is the 10001st prime number? …
The Difference Between Sum of Squares and Square of the Sum
The sum of the squares of the first ten natural numbers is, 1^2+2^2+3^2+…10^2=385 The square of the sum of the first ten natural numbers is, (1+2+…+10)^2=55^2=3025 Hence the difference …