A mirror 2cm long and 1cm wide is mounted on a wall of 6cm long and 3cm high. How many mirror is needed to cover the wall?
This wall and mirror must be in a doll-house.
anyway...
area of mirror = 2*1 or 2 cm^2
area of wall = 6*3 or 18 cm^2
number of mirrors needed = 9
or think of it this way:
the wall is 6 cm long, so you need 3 mirrors along the base
the wall is 3 cm high, and the mirror is 1 cm high, so you need 3 rows of 3 each, or 9 of them