The perimeter of any shape is the sum of all the sides of the shape.
The perimeter of a square is the sum of all four equal lengths. It is given by the formula
From the question, the length, l=14mm.
![\begin{gathered} P_{\text{square}}=4*14\operatorname{mm} \\ P_{\text{square}}=56\operatorname{mm} \end{gathered}]()
Hence, the perimeter of the square that has a side length of 14mm is 56mm