Calculate the principal amount if the simple interest is 648 रुपये, the rate is 12% per annum, and the time is 3 years.

The problem states the following:

• Simple Interest (SI) = 648 रुपये
• Rate of Interest (R) = 12% per annum
• Time (T) = 3 years

The formula for simple interest is:

$$SI = \frac{P \times R \times T}{100}$$

Where $P$ is the Principal amount.

To find the principal amount, we can rearrange the formula:

$$P = \frac{SI \times 100}{R \times T}$$

$$P = \frac{648 \times 100}{12 \times 3}$$ $$P = \frac{64800}{36}$$ $$P = 1800$$

The principal amount is 1800 रुपये.

Comparing this with the given options:

1. 2100
2. 1100
3. 1800
4. 2200

The calculated principal matches option 3.

The final answer is $\text{3) 1800}$.