0
If you meant 1 − 1, the result is 0. Quick check: on a number line, starting at 1 and moving left by 1 unit lands you at 0.
If “1-1” was referring to something else (a problem number, a fraction, or a specific exam question), please share the full question or context and I’ll walk you through it. Would you like a quick refresher on subtraction or how to approach similar problems?