Step 1: Start with the fraction 100/21.

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

100 ÷ 21 = 4.7619

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

4.7619 × 100 = 476.19%

Final Answer: 100/21 as a percentage is 476.19%.