Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the smallest (or largest) sum. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the smallest (or largest) difference. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the smallest (or largest) quotient. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the smallest (or largest) product. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the smallest (or largest) quotient. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the smallest (or largest) sum. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the smallest (or largest) difference. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the smallest (or largest) product. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to create the smallest possible difference. Source: Graham Fletcher

Directions: Using the digits 0 to 9, at most one time each, place a digit in each box to make the equation true. Source: Graham Fletcher