Milk is sold at the rate of Rs `42.50` per litre. How much will `12.5` litres of milk cost ?

Answer

To find the cost of 12.5 litres of milk sold at the rate of Rs 42.50 per litre, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Cost per Litre**:
The cost of 1 litre of milk is given as Rs 42.50.

2. **Determine the Quantity of Milk**:
We need to calculate the cost for 12.5 litres of milk.

3. **Set Up the Multiplication**:
To find the total cost, we will multiply the cost per litre by the number of litres:
\[ \text{Total Cost} = \text{Cost per Litre} \times \text{Quantity in Litres} \]
\[ \text{Total Cost} = 42.50 \times 12.5 \]

4. **Perform the Multiplication**:
Now we will calculate \( 42.50 \times 12.5 \):
- First, ignore the decimal and multiply as if they are whole numbers:
\[ 4250 \times 125 \]
- Calculate step by step:
- \( 0 \times 5 = 0 \)
- \( 0 \times 2 = 0 \)
- \( 0 \times 4 = 0 \)
- \( 5 \times 5 = 25 \) (write down 5, carry over 2)
- \( 5 \times 2 = 10 + 2 = 12 \) (write down 2, carry over 1)
- \( 5 \times 4 = 20 + 1 = 21 \) (write down 21)
- So, the first row is 53125.
- Now, we need to place the decimal point. Since we multiplied 42.50 (which has 2 decimal places) by 12.5 (which has 1 decimal place), the total number of decimal places is 3.
- Therefore, we place the decimal point in 53125 to get 531.25.

5. **Final Answer**:
The total cost of 12.5 litres of milk is Rs 531.25.

### Summary:
The cost of 12.5 litres of milk at Rs 42.50 per litre is **Rs 531.25**.

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