The perimeter of the shaded figure made out of 9-unit squares is equal to 20. What is the greatest number of squares we can connect to the shaded area so that the perimeter of the new figure would still be 20?
Hint: Try to think visually. What happens when we shift these squares?
We can make it a square with each side having 5-unit squares. So, the perimeter would remain at 20. Hence, we can include 16 more small squares.
Note: The kind of problems belongs to logical reasoning with small knowledge of perimeter. Even if we don’t know these then brainstorming will give the answer.