Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make a sum with the greatest possible value. Source: Owen Kaplinsky and Robert Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the equation true. Source: Owen Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the equation true. Source: Owen Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make 5 composite numbers. Source: Owen Kaplinsky

Directions: Using the digits 1 to 9, exactly two times each, place a digit in each box to create a nine digit number and its corresponding place values. Source: Owen Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the equation true. Source: Owen Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the equation true. Source: Owen Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make three equivalent fractions. Source: Graham Fletcher, Bowen Kerins

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make 5 prime numbers. Source: Owen Kaplinsky

Directions: Using the digits 1 to 6, at most one time each, place a digit in each box to make the largest value for D (the derivative). Source: Chris Luzniak