To calculate 15% of a number, you simply multiply the number by $0.15$.

Understanding how to find 15% of a number requires a grasp of percentages and basic multiplication. A percentage represents a part of a whole, specifically a fraction out of 100. Thus, $15\%$ indicates 15 out of every 100. To convert a percentage into a decimal, you divide by $100$. For $15\%$, this calculation is $15 \div 100 = 0.15$.

With the decimal form established, you can find 15% of any number by multiplying it by $0.15$. For example, to determine 15% of $200$, you would perform the calculation $200 \times 0.15$. The result is $30$, which means that $15\%$ of $200$ equals $30$.

Alternatively, you can break down the calculation into simpler steps. Start by finding $10\%$ of the number by dividing it by $10$. For instance, $10\%$ of $200$ is $20$. Next, calculate $5\%$ by halving the $10\%$ value. In this case, $5\%$ of $200$ is $10$. Finally, add these two results together: $20$ (from $10\%$) plus $10$ (from $5\%$) equals $30$. This confirms that $15\%$ of $200$ is indeed $30$.

This method is versatile and can be applied to any number, making it a valuable skill for various real-life scenarios, such as calculating discounts, interest rates, or proportions in recipes.