Perimeter is a calculation of all the outer side of the shapes .

Formula for perimeter -> Length of Outer side **+** length of outer side = ____cm @ m.

Let's us view another example :

The calculation for this shape is :

12cm **+** 10cm **+ **3cm **+ **6cm **+ **6cm ( 12cm - 3cm - 3cm ) **+ **6cm **+ **3cm **+ **10cm = 56cm .

It is really simple , is it ?

Remember ! Perimeter only uses **'+****' **.

If the shape is square , you can multiply the length of outer side .