Area | Mathematics for Grade 4 PDF Download

Concept of Area

Take a plate and cover it with the cookies. How many cookies do you need to cover the plate? Now, take another plate of a different size. Which plate needs more cookies? Which plate has a larger surface?
Rahul wrapped 2 gifts. He found that bigger gift required more wrapping paper, whereas the smaller gift required less wrapping paper. So, by area we mean, the flat surface which you cover or paint.Thus, area is the measure of the region inside a plane figure.

Finding Area using Square Tiles

Ms Sharma wanted to know the area of her porch floor. She started, by putting square floor tiles on the floor.

Q1: How many more tiles will it take to cover the floor?
Ans: 6

Q2: How many tiles will be used altogether?
Ans: 48
An object such as a square paper sheet or a square floor tile can be used to find the area. A square and its interior is called a square unit for finding area.
Thus, area of a region can be found by finding the number of square units needed to cover the interior of a figure.

Example 1: Find the area of each of the following regions by counting squares.

Sol:
Mark the squares in the figures:
(a) Since there are 7 squares in the figure,

∴ Area of the given figure = 7 square units.
(b) Since there are 8 squares in the figure,
∴ Area of the given figure = 8 square units.
(c) Since there are 13 squares in the figure,
∴ Area of the given figure = 13 square units.
(d) Since there are 12 squares in the given figure,
∴ Area of the given figure = 12 square units.

Area of a Rectangle

Look at the following rectangle whose length is 7 cm and breadth is 3 cm.
To find its area, we can divide it into 3 rows of 7 squares each or 7 columns of 3 squares each.By counting the number of squares, we can find the area of the rectangle. Since the rectangle contains 21 squares, so its area = 21 square centimetre.Note that, if we multiply the length (l) = 7 cm and breadth (b) = 3 cm, then we get the product as 21 square centimetre.
Therefore,  Area of a rectangle = length × breadth = l × b.

Area of a Square

If we divide a square of side 5 cm into small squares by dividing it into 5 rows and 5 columns, we get 25 small squares each of length 1 centimetre.

∴ Area of the square = 25 sq cm (by counting).Also, on multiplying 5 cm by 5 cm, we get, 25 sq cm.
Therefore, Area of a square = side × side.

Example 1: Find the area of a rectangle with length 12 cm and breadth 4 cm.

Sol:
Area of rectangle = l × b

= 12 cm × 4 cm = 48 sq cm.

Example 2: Find the length of a rectangle whose area is 48 sq cm and breadth is 8 cm.

Sol:
Area = Length × Breadth

Example 3: Find the area of a square field of side length 70 m?

Sol:
Area of square = Side × Side  
= 70 m  × 70 m = 4900 sq m.