Step 1: Start with the fraction 4/10.

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

4 ÷ 10 = 0.4

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

0.4 × 100 = 40.0%

Final Answer: 4/10 as a percentage is 40.0%.