You can read posting Sarin learns Perimeter, Area and Volume in school(Math Concept) to learn the concept of perimeter, area and volume.
Read also posting on Sarin learns Shapes and Solids in school (Math Concept) to know about shapes.
Upper primary school mathematics question UPQ100
PQRS is a square of side 14 cm. A circle inside as shown in the diagrm. What is the area of the shaded part?
The area of the square = 14 × 14 = 196cm2
The area of the circle = 22/7 × 7 × 7 = 154cm2
The area of the shaded part = 196 – 154 = 42cm2