[Note: This kind of puzzle is due to Wei-Hwa Huang and a 4 by 4 puzzle appears every Sunday (2016) in the New York Times Magazine]

• Problem 1
• Problem 2
• Problem 3
• Problem 4
• Problem 5
• Problem 6
• Problem 7
• Problem 8
• Problem 9
• Problem 10
• Problem 11
• Problem 12
• Problem 13
• Problem 14
• Problem 15
• Problem 16
• Problem 17
• Problem 18
• Problem 19
• Problem 20