Step 1: Start with the fraction 21/20.

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

21 ÷ 20 = 1.05

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

1.05 × 100 = 105.0%

Final Answer: 21/20 as a percentage is 105.0%.