If the total interest becomes Rs. $x$ for any principal having the rate of simple interest of $x\%$ per annum for $x$ years then the principal will be

The formula for simple interest is:
$$\text{SI}=\frac{P\times R\times T}{100}$$

Given:

* Simple Interest ($\text{SI}$) = $x$
* Rate of interest ($R$) = $x\%$
* Time ($T$) = $x$ years

Substituting these values into the formula:

$$x=\frac{P\times x\times x}{100}$$

$$x=\frac{P\times x^2}{100}$$

Solving for the principal ($P$):

$$P=\frac{100x}{x^2}=\frac{100}{x}$$

Thus, the principal amount is Rs. $\frac{100}{x}$.