The most common opening move in checkers is to move the front central piece two spaces forward.
The most common first move in chess that involves moving the knight to f3 is called the Reti Opening.
they do not have anything in common
The mouth is the common opening for the food pipe and windpipe.
squares of prime numbers
The squares can have sides equal to each factor that is common to both numbers.
Forward head posture in common but very destructive to the spine.
All their roots are whole numbers.
Any number squared except 0 is a perfect square so it follows that prime numbers are less common than perfect squares.
They are both perfect squares less than 100.
All have 90 degree angles.
"Grand opening" is a common noun. It refers to a general event or occasion marking the official opening of a business or establishment. It is not capitalized unless it is part of a specific title or name, such as "Grand Opening of Joe's Coffee Shop."