How many square slabs of side 90 cm are needed to cover floor of area 81 sq m?
Step 1: Convert the floor area to cm² (same unit as the slab).
We know:
(1 ext{ m} = 100 ext{ cm})
So, (1 ext{ m}^2 = 100 ext{ cm} imes 100 ext{ cm})
(= 10{,}000 ext{ cm}^2)
Given floor area (= 81 ext{ m}^2)
(81 ext{ m}^2 = 81 imes 10{,}000 ext{ cm}^2)
(= 810{,}000 ext{ cm}^2)
Step 2: Find the area of one square slab.
Side of slab (= 90 ext{ cm})
Area of slab (= ext{side} imes ext{side})
(= 90 ext{ cm} imes 90 ext{ cm})
(= 8{,}100 ext{ cm}^2)
Step 3: Find how many slabs are needed.
( ext{Number of slabs} = dfrac{ ext{Total floor area}}{ ext{Area of one slab}})
(= dfrac{810{,}000}{8{,}100})
(= 100)
Answer: 100 slabs are needed (assuming perfect fit with no gaps or cutting).