Step 1: Start with the fraction 12/18.

Step 2: To convert a fraction into a percentage, divide the numerator by the denominator.

12 ÷ 18 = 0.6667

Step 3: Multiply the result by 100 to get the percentage.

0.6667 × 100 = 66.67%

Final Answer: 12/18 as a percentage is 66.67%.