🧱 Question 56: How Many Bricks Are Needed?

Q56: How many bricks will be required for a wall 8 m long, 6 m high, and 22.5 cm thick, if each brick measures 25 cm × 11.25 cm × 6 cm?

Options:
(a) 640
(b) 1380
(c) 6400
(d) 7600

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📝 Step 1: Convert all dimensions to the same unit

We have:

• Wall: 8 m × 6 m × 22.5 cm

• Brick: 25 cm × 11.25 cm × 6 cm

Tip: Always use the same unit. Let’s use cm:

$$1 \text{ m} = 100 \text{ cm}$$

Wall dimensions in cm:

• Length = 8 × 100 = 800 cm

• Height = 6 × 100 = 600 cm

• Thickness = 22.5 cm (already in cm)

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📝 Step 2: Find the volume of the wall

$$\text{Volume of wall} = \text{length} \times \text{height} \times \text{thickness}$$ $$V_\text{wall} = 800 \times 600 \times 22.5$$

Step by step:

1. 800 × 600 = 480,000

2. 480,000 × 22.5 = 10,800,000 cm³

✅ Volume of the wall = 10,800,000 cm³

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📝 Step 3: Find the volume of one brick

$$V_\text{brick} = 25 \times 11.25 \times 6$$

Step by step:

1. 25 × 11.25 = 281.25

2. 281.25 × 6 = 1,687.5 cm³

✅ Volume of one brick = 1,687.5 cm³

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📝 Step 4: Find the number of bricks

$$\text{Number of bricks} = \frac{\text{Volume of wall}}{\text{Volume of one brick}}$$ $$\text{Number of bricks} = \frac{10,800,000}{1,687.5} = 6400$$

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✅ Answer:

Q56 Answer: (c) 6400

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💡 Quick Tips for Brick Problems

1. Convert all dimensions to the same unit (cm or m).

2. Find the volume of the wall and one brick.

3. Divide wall volume by brick volume.

4. Check if the answer makes sense (thousands of bricks for a big wall is reasonable!).