Find the surface ara of a chalk box, whose length, breadth and height are 18 cm, 10 cm, and 8 cm respectively.

Answer

To find the surface area of a chalk box, which is in the shape of a cuboid, we will follow these steps:

### Step 1: Identify the dimensions of the cuboid.
- Length (L) = 18 cm
- Breadth (B) = 10 cm
- Height (H) = 8 cm

### Step 2: Write down the formula for the total surface area (TSA) of a cuboid.
The formula for the total surface area of a cuboid is:
\[ TSA = 2(LB + BH + HL) \]

### Step 3: Substitute the values of length, breadth, and height into the formula.
Substituting the values we have:
\[ TSA = 2(18 \times 10 + 10 \times 8 + 8 \times 18) \]

### Step 4: Calculate the products inside the parentheses.
- Calculate \( 18 \times 10 = 180 \)
- Calculate \( 10 \times 8 = 80 \)
- Calculate \( 8 \times 18 = 144 \)

Now, substituting these values back into the equation:
\[ TSA = 2(180 + 80 + 144) \]

### Step 5: Add the results from Step 4.
Now, add the three products:
\[ 180 + 80 = 260 \]
\[ 260 + 144 = 404 \]

### Step 6: Multiply the sum by 2.
Now, we multiply the sum by 2 to find the total surface area:
\[ TSA = 2 \times 404 = 808 \, \text{cm}^2 \]

### Final Answer:
The total surface area of the chalk box is \( 808 \, \text{cm}^2 \).

---