The Mystical Squares

Consider a 3×3 square where each 1×1 square is filled with one of the integers 1,2,3 or 4. A square is called mystical if each row and column sum up to a multiple of 4. How many mystical squares are there?

Details and assumptions

Rotations and reflections of the square are considered distinct solutions.

Squares Form a Rectangle

Squares and Rectangle

2 squares, each of area 16, are joined side by side to form a rectangle. What is the perimeter of the rectangle?

Collecting coins

How many ways are there for a collection of exactly 100 coins (pennies, nickels, dimes or quarters) to total $2.99?

Note: Pennies are worth $0.01, nickels are worth $0.05, dimes are worth $0.10 and quarters are worth $0.25.