Page 344 - Math Smart - 7

Example 5

Kane calculates the area of an envelope using his ruler and got an answer of
150 cm^ But the post office wants the area in in mm^ Help Kane convert his
answer from cm^ to mm^.

Solution
10mm - 1cm
To convert cm to mm, we multiply by 10.
10 mm X 10 mm
To convert cm^ to mm^ we multiply by 10^ because there are 100 mm^ in 1 cm'
= 1 cm X 1 cm
So, to convert 150 cm^to mm^ multiply by 100.
So, 100 mm^ = 1 cm^.
150 X 100= 15 000 mm^

Find the area of the rectangle in cm^. 8 mm

3 mm
Solution
Method 1
8 mm = 0.8 cm 3 mm = 0.3 cm
Area = 0.8 x 0.3
= 0.24 cm^
10 mm^= 0.10 cm^ f
S^m^= 0.24 cm^ | Method 2
To convert 24 mm^ to cm^ : Area = 8 mm x 3 mm
divide by 100. | = 24 mm^

= 0.24 cm^

Find the area of the square in m' 5 cm

5 cm

Solution
Method 1
5 cm = 0.05 m
Area = 0.05 x 0.05 = 0.002 5 m^
fyry^
0.001 0 m
Method 2
25 cm2= 0.002 5 m
Area = 5 cm x 5 cm
To convert 25 cm^ to m^
= 25 cm^
divide by 10 000.
= 0.002 5 m^

Measuring Time, Area, Perimeter and Volume