What are some common errors or mistakes to avoid when using PHP to simulate and solve mathematical problems involving percentages and sums?

One common mistake when working with percentages in PHP is forgetting to convert percentages to decimals before performing calculations. To avoid errors, always remember to divide the percentage by 100 before using it in mathematical operations. Additionally, ensure that you are correctly adding or subtracting percentages from sums by properly calculating the percentage amount based on the given value.

// Incorrect way to calculate a percentage
$amount = 100;
$percentage = 20;

// Incorrect calculation
$total = $amount + ($amount * $percentage);

// Correct way to calculate a percentage
$amount = 100;
$percentage = 20;

// Convert percentage to decimal
$decimalPercentage = $percentage / 100;

// Correct calculation
$total = $amount + ($amount * $decimalPercentage);