Write the least positive integral value of `n` for which `((1+i)/(1-i))^n` is real.

Explanation

To find the least positive integral value of \( n \) for which \( \left( \frac{1+i}{1-i} \right)^n \) is real, we can follow these steps:

### Step 1: Simplify the expression
We start with the expression:
\[ \frac{1+i}{1-i} \]
To simplify this, we multiply the numerator and the denominator by the conjugate of the denominator, which is \( 1+i \):
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